Patent Publication Number: US-2011050391-A1

Title: Electronic Access Control Device and Management System

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/137,257, filed May 25, 2005, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/885,998, filed Jul. 7, 2004, and issued as U.S. Pat. No. 7,482,907, which is a continuation of co-pending U.S. patent application Ser. No. 10/024,945, filed Dec. 19, 2001, and issued as U.S. Pat. No. 6,977,576, which is a continuation of U.S. patent application Ser. No. 08/760,062, filed Dec. 4, 1996, and issued as U.S. Pat. No. 6,359,547, which is a continuation-in-part of U.S. patent application Ser. No. 08/339,555, filed Nov. 15, 1994, and issued as U.S. Pat. No. 5,617,082. 
     This application is also a continuation-in-part of co-pending U.S. patent application Ser. No. 12/261,843, filed Oct. 30, 2008, which is a continuation of U.S. application Ser. No. 11/185,110, filed Jul. 20, 2005, and now abandoned, which is a continuation-in-part of (1) U.S. application Ser. No. 11/010,661, filed Dec. 13, 2004, and issued as U.S. Pat. No. 7,373,352, which claims priority of U.S. Provisional Application 60/528,831, filed Dec. 11, 2003, and (2) U.S. application Ser. No. 10/838,449, filed May 4, 2004, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/329,626, filed Dec. 26, 2002, and issued as U.S. Pat. No. 6,900,720, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/344,221, filed Dec. 27, 2001. 
     This application is also related to co-filed U.S. patent application Ser. Nos. 12/853,721 and 12/853,739, filed Aug. 10, 2010. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates to electronic devices for accessing or otherwise controlling functions of devices that operate in the field (“field devices”), such as vending machines, coolers, fountain dispensers, storage boxes, shipping containers, power tools, etc., and more particularly to a system and method wherein the field devices are controlled by one or more microprocessors and can be operated by a wireless electronic key, and for controlling and managing operations of field devices that collect location information and uses the location information and other parameters for controlling the operations of the field devices. 
     BACKGROUND OF THE INVENTION 
     An electronic access control device, such as an electronic combination lock or an electronic alarm system, allows the user to activate or deactivate the access control without the use of the conventional key and mechanical lock mechanism. With the development of microprocessor integrated circuits, it is becoming common to implement microprocessor-based control circuitry in electronic access control devices. Electronic access control devices are known, for example, from U.S. Pat. No. 5,021,776. In this device, and other common electronic access control devices, a microprocessor is used in combination with a keypad and an electrically programmable read only memory (EPROM). The microprocessor compares the combination entered in the keypad by the operator with the combination stored in the EPROM. If the two combinations match, the microprocessor opens the lock. 
     There are problems associated with previous electronic access control devices. One area of problems concerns the manufacture of the devices, including the difficulty in programming the non-volatile memory, such as the EPROM, for storing the access code and other useful information for the operation of the device. EPROMs, which usually require parallel programming, interrupt the manufacturing process in that they restrict when the manufacturer can program the device. A manufacturer would prefer to program the access code into the EPROM as the last step in the manufacturing process. However, with parallel EPROMs, burning in the code after the device has manufactured is difficult. After the device is soldered together, the manufacturer must contend with integrated circuit pin clips and must worry about interference with other circuitry on the manufactured device. Further, manufacturing, with known electronic access control devices, requires many pin connections which increase manufacturing cost. 
     Related to the problems associated with the pin connections of the microprocessor integrated circuit (IC) is the concern of device reliability and ease of use. When the device contains a significant number of pin connections, the reliability of the device decreases. Further, serial access to the EPROM to determine the electronic access code is easier than parallel access in terms of pin connections. When the user forgets or loses the access code in the EPROM, a locksmith could plug into the device and retrieve the access code serially without breaking into the safe. However, with parallel EPROMs, serial access is not available. 
     One common problem associated with previous electronic locks is their potential vulnerability to tampering. A conventional electronic lock receives an access code via an input device such as a keypad or electronic key reader, verifies the access code, and then energizes a solenoid, relay, motor, or the like to open the lock. This arrangement is vulnerable to tampering because if the control circuit is somehow broken in or removed, one can open the lock by “hot-wiring” the control lines for activating the lock-opening mechanism. 
     Another technically challenging problem is related to the need to provide electrical energy to power the operation of the electronic access control device. For many applications, it is desirable to use a portable or alternative energy source, such as a battery, to power the access control device. A battery, however, has a rather limited amount of electrical energy stored therein. Thus, in many applications it is important to reduce the power consumption of the control circuit and peripheral devices of the access control device to extend the service life of the batteries. 
     For instance, it is typical to use a solenoid-operated lock in an electronic lock. The consumed by the solenoid in opening the lock is quite significant. Thus, the battery can be rapidly drained by the repeated operation of the solenoid. As another example, it is common to include a low-battery detection circuit in an electronic lock to provide a warning signal to the user when the battery voltage falls below a predetermined level. The operation of the low-battery detection circuit, however, also consumes electrical energy and contributes to the draining of the battery. 
     Some electronic locks are provided with electronic keys. When an electronic key is presented to a key reader of an associated electronic lock, it transmits an access code to the electronic lock. By using an electronic key, the user does not have to enter manually the access code by means of a keypad. In certain applications, a remote control unit is used which has a radio transmitter to send the access code to the lock without direct electrical contact with the electronic lock. 
     Although electronic keys are a convenient feature, they have their associated problems. One problem is related to the unauthorized use of the keys. For example, many hotels provide safes equipped with electronic locks in their hotel rooms. Such safes typically allow the hotel guests to set their own access codes. In cases where the hotel guests forget the access codes they set, the hotel management has to send someone with a master key which has a master access code stored therein to open the safes. There is a danger that such a master key may be used for unauthorized opening of other safes in the hotel. 
     Another problem associated with the use of an electronic key or a wireless access code transmitter is that the key or the transmitter may be lost easily, or the user may simply forget to bring the key or transmitter. This problem is especially serious if the electronic access control device does not provide other means, such as a keypad, for entering the access code. 
     Vending machines are widely used in various locations as automated means for selling items such as soft drinks, snacks, etc. Traditional vending machines are equipped with mechanical locks, which can be unlocked with a corresponding mechanical key to open the door of the machine to allow reloading of goods and collection of money. 
     One significant problem with conventional vending machines is the difficulties in managing the distribution and usage of the keys to ensure the security of the locks on the vending machines. The process of collecting money from the vending machines scattered at different places is a very manpower-intensive operation that requires many employees to go into the field with numerous mechanical keys for operating the locks on the vending machines. It requires a considerable amount of attention and efforts to manage and track the distribution of the keys to the field workers to keep the keys secure. 
     Moreover, the mechanical keys and lock cores of vending machines are a point of attack for vandals. The keys can be lost or copied easily, and the stolen or copied keys may then be used by an unauthorized person to access the machines, and it is difficult to discover such misuses and security breaches. Also, a skilled vandal can easily pick or drill-out the lock core tumblers and measure the key cuts of the lock core tumblers to re-produce a like key and compromise the security. In the event a security breach is identified, the mechanical lock cores of the affected vending machines typically have to be manually replaced, which is a time-consuming and very costly process. Furthermore, mechanical keys and locks are devices that cannot be partially limited in operation they operate indefinitely if in use. Also, they do not have the ability to record access operation attempts of their operation. 
     In addition, appliances, such as vending machines, fountain drink dispensers, coolers, etc., are used in various commercial settings, and there is always a need to control access to or operations of those devices. For instance, vending machines have to be serviced on a regular basis to replenish goods and collect money, and it is necessary to control the access to the machines so that only authorized personnel may open the machines at allowed times. As another example, it may be desirable to control the operation of a given appliance, such as a fountain drink dispenser, such that the appliance cannot be used unless the authorization for its usage is renewed. Moreover, in many cases, it is desirable to be able to monitor the location of an appliance such that its access or usage can be denied if the appliance has been stolen or otherwise removed from its intended location. Similar needs to control the access and operations of other devices used in the field, such as power tools, storage boxes, shipping containers, etc., based on various parameters such as time, location, number of access, personnel authorization, etc., are also felt in many different industries. 
     SUMMARY OF THE INVENTION 
     It is a general object of the present invention to develop an electronic access control device which is easier to manufacture and more reliable to operate, and provides improved security to prevent tampering or unauthorized access. 
     It is an object of the present invention to provide an electronic access control device with a non-volatile memory for storing an access code that permits the manufacturer of the device to easily insert the access code into the device and then read out the code for verification. 
     It is an object of the present invention to provide an electronic access control device that provides significantly enhanced security and reduced vulnerability to tampering as compared to previous electronic locks. 
     It is an object of the present invention to develop an electronic access control device which has fewer total components and pin connections for smaller device area and greater reliability. 
     It is another object of the present invention to develop an electronic access control device with a solenoid-operated lock which has reduced power consumption by reducing the power used in operating the solenoid. 
     It is a related object of the present invention to develop an electronic access control device that has an improved low-battery detection circuit which has minimized energy consumption. 
     It is another more specific object of the present invention to provide an electronic access control system with a master key for a plurality of remote electronic locks that effectively prevents the unauthorized use of the master key. 
     It is also a general object of the invention to provide a system and method for accessing or controlling operations of devices in the field that enables the use of location information to determine whether a field device should be accessed or enabled to operate based on the location and other operation limit parameters. 
     The present invention accomplishes these and other objects and overcomes the drawbacks of the prior art. First, there is provided an electronic access control device which reduces the number of pin connections required to manufacture, to read, to program, and to operate the device. The device multiplexes the inputs and outputs of the microprocessor IC so that a single pin can function as an input in one mode and an output in another. The microprocessor determines, based on the mode of operation, whether a pin functions as an input or an output. 
     The electronic access control device of the present invention has a communication port connected to selected pins of the microprocessor IC for accessing the non-volatile memory for storing an access code. Through the communication port, the manufacturer can interact with the microprocessor to store an access code into the non-volatile memory and retrieve the access code for verification. By virtue of the provision of the communication port, the factory-programmed access code can be saved into the non-volatile memory after the control circuitry is completely assembled. 
     In one embodiment, the electronic access control device has a microprocessor IC with a plurality of pins, a keypad for inputting user-entered access codes and a non-volatile memory, such as an EEPROM, external of the microprocessor for storing an access code. At least one of the IC pins is connected to both the keypad and the non-volatile memory for receiving the user-entered code from the keypad and transferring data between the IC and the memory. 
     In accordance with the object of the invention to reduce the vulnerability to tampering, the present invention provides an electronic access control device which has two microprocessors. The first microprocessor is preferably disposed close to the user interface such as a keypad or an electronic key reader. The second microprocessor is preferably disposed close to the lock mechanism and substantially shielded from external access. When the first microprocessor receives a user-entered code, it compares the entered code to a stored access code. If those two codes match, the first microprocessor transmits a special communication code to the second microprocessor. The second IC opens the lock if the transmitted communication code matches a stored communication code. Since the second IC is well protected from external access, the risk of tampering by hard-wiring is significantly reduced. 
     This dual-microprocessor arrangement is advantageously used in a voice activated access control system which has a first microprocessor circuit having speech recognition capability, and a second microprocessor circuit which carries out a commanded operation when receiving a correct communication code from the first microprocessor circuit. The first microprocessor circuit may include a transmitter for wireless transmission of the communication code. 
     The present invention also provides an effective solution to the problem associated with the intensive need for power of the solenoid. In the present invention, the electronic access control device pulses the power to the solenoid so that the overall power consumption in operating the solenoid is lower. Thus, the battery has a longer life and the lock has an increased number of accesses. 
     In accordance with a related aspect of the present invention, the electronic access control device employs a low-battery detection circuit that is turned off and therefore consumes no electrical power when the microprocessor is in the sleep mode. The low-battery detection circuit uses a combination of a voltage divider and a transistor to compare the battery voltage and the regulated voltage for determining whether the battery voltage is low, and uses another transistor in series with the voltage divider to selectively turn the current through the voltage divider on and off. When the current through the voltage divider is off, the low-voltage detection circuit does not consume electrical energy. 
     In the case of an electronic access control system with a master key and a plurality of remote electronic locks, the present invention effectively prevents unauthorized use of the master key. In accordance with the present invention, the master key has a master access code and a number of access stored therein. Each of the remote electronic lock has a key reader to communicating with the master key. When an electronic lock detects in the key a correct master access code and a number of access that is at least one, it opens the associated lock and decrements the number of access in the key by one. 
     In view of the foregoing, the present invention can provide a vending machine with a field-programmable electronic lock. The electronic lock can learn a key code from a corresponding electronic key. Alternatively, the electronic lock can learn that it should be accessed by an electronic switch controlled by a mechanical lock that can be opened with an associated mechanical key. The electronic lock has a learning process activation device that is accessible only when the door of the vending machine is in the open position. Using the learning process activation device, a service person sets the electronic lock in a learning mode, in which the electronic lock receives a key code transmitted from an electronic key, and stores the key code in a non-volatile memory for future access control of the vending machine. In the case where the lock access is to be controlled by the switch-lock combination, during the learning process the electronic lock controller receives an electronic closure signal from the switch. The lock thus learns that it is to open the door of the vending machine in response of the switch signal in lieu of reception of key codes from electronic keys. 
     The key-learning process in accordance with the invention allows electronic locks in vending machines to be easily and inexpensively programmed in the field. Thus, the electronic locks do not have to be manufactured with pre-defined permanent key codes and are not tied to any specific electronic keys for field use. There is no need to replace any physical part of the electronic lock in this key-learning process to learn a new key code and/or replacing an old key code. In contrast, mechanical locks conventionally used on vending machines have lock cores that have to be manufactured for specific keys, and once manufactured the lock cores cannot be changed. If the mechanical key is lost, the entire lock cores have to be replaced. More than one electronic key can possess a given keycode. The electronic lock on a vending machine can allow more than one keycode to be learned into the lock and used to access the lock. 
     The use of the field-programmable electronic locks for vending machines provides an effective way to reduce theft and fraud in terms of unauthorized access to the machines. The electronic keys provide a greater level of key security compared to mechanical keys, as they cannot be copied as easily as conventional mechanical keys. The use of non-contact wireless data communication between the key and the lock prevents breeches of security associated with vandals measuring key cuts, copying keys and picking locks. The use of data encryption in the wireless communications between the key and the lock prevents the key code from being copied by electronic monitoring and eavesdropping. The data transmission between the key and lock may be implemented in the infrared range to provide close-proximity highly directional communication of secure codes to further prevent eavesdropping of the security codes and to prevent accidental unlocking of locks. 
     The use of programmable electronic locks on vending machines and the associated electronic keys also provides advantages in terms of significant reduction in the costs associated with managing the distribution of the keys for unlocking the machines and the monitoring of the usage of the keys. Key IDs in addition to the key codes used in accessing the lock may be used to distinguish keys having the same key codes. Customized access limitations may be programmed by a supervisor into the electronic keys to restrict when and how they can be used to access the vending machines. Each key may also be programmed with a specific list of lock IDs identifying the electronic locks on vending machines that the key is allowed to unlock. 
     In accordance with one aspect of the invention, a history of access attempts may be stored in each of the electronic key and the electronic lock for audit purposes. The key may store the access history each time it is used to access an electronic lock on a vending machine. Likewise, each electronic lock on a vending machine may store audit data regarding the access attempts directed to it. The audit data may be transferred from the electronic lock to the electronic key during an unlocking operation, and the audit data of different vending machines collected by an electronic key can be later downloaded to a computer for analysis. 
     In accordance with another aspect of the invention, the electronic lock may accept more than one type of keys and corresponding key codes. The different key types may be associated with different levels of security of the unlocking operations and the type of data transmitted between the key and lock during the unlocking operations. 
     In accordance with another aspect of the invention, the electronic lock in a vending machine can work in conjunction with an electronic communication device in the vending machine that is in wireless communication with a home base to accomplish many of the same access control, auditing, and additionally some inventory and money settlement processes. 
     In accordance with a further aspect of the invention, a mobile control device, such as an electronic key, is used to access or otherwise control the operations of a field device, such as a vending machine, fountain drink dispenser, power tool, storage or shipping container, etc. In a control event in which the mobile control device interacts with the field device to apply the control, the control device receives location information and the ID of the field device, and uses the location data in determining whether the field device should be accessed or enabled. The communication between the mobile control device and the field device may be secured with encryption. The mobile control device may record the location information and the device ID in a control event record which may be later downloaded for auditing. Alternatively, the time-dependent location information may be stored separately in a location sensing device. The control event data and the location information are then downloaded into a management system and combined therein. 
     These and other features and advantages of the invention will be more readily apparent upon reading the following description of the preferred embodiment of the invention and upon reference to the accompanying drawings wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an electronic access control device having a keypad; 
         FIG. 2  is a block diagram of the electronic access control device of  FIG. 1 ; 
         FIG. 3  is the schematic of the electronic access control device; 
         FIG. 4  is the flow chart at power-up of the device; 
         FIG. 5  is the flow chart of the device in normal operation; 
         FIG. 6  is a block diagram of a remote access control device; 
         FIG. 7  is a schematic of the input electronics of the remote access control device of  FIG. 6 ; 
         FIG. 8  is a schematic of another embodiment of the electronic control access device which has a non-volatile memory sharing certain pins of a microprocessor with a keypad; 
         FIG. 9  is a functional block diagram showing an embodiment of an electronic access control device having two microprocessors communicating with each other to provide enhanced security of the device; 
         FIGS. 10A and 10B  are schematic views together showing an application of the dual-microprocessor configuration of  FIG. 9  in an electronic combination lock; 
         FIG. 11  is a functional block diagram showing an application of the dual-microprocessor configuration of  FIG. 9  in an ignition control system for a motorcycle; 
         FIG. 12  is a functional block diagram showing an application of the dual-microprocessor configuration of  FIG. 9  in a voice controlled access control device; 
         FIG. 13  is a functional block diagram showing another embodiment of the voice controlled access control device; 
         FIG. 14  is a functional block diagram showing another embodiment of the voice controlled access control device which has a central control station and remote devices; 
         FIG. 15  is a schematic view showing an electronic access control system which has a master key for opening a plurality of remote electronic locks; 
         FIG. 16  is a schematic view of an electronic alarm system for a bicycle which has a remote control unit mounted in a riding helmet and an electronic alarm mounted on the bicycle; 
         FIG. 17  is a schematic view of a vending machine and an electronic key for opening an electronic lock inside the vending machine; 
         FIG. 18  is a perspective view of an electronic lock assembly mounted on a door of a vending machine; 
         FIG. 19  is a block diagram showing electronic circuit components of an electronic lock used in a vending machine; 
         FIG. 20  is a block diagram showing electronic circuit components of an electronic key; 
         FIGS. 21A and 21B  are schematic diagrams showing key codes stored in the memories of an electronic key and an electronic lock, respectively; 
         FIG. 22  is a schematic diagram showing the transmission of data between an electronic lock on a vending machine and an electronic key during a simplified unlocking process; 
         FIG. 23  is a schematic diagram showing communications between an electronic lock on a vending machine and an electronic key during an unlocking process that has higher security than the process in  FIG. 22 ; 
         FIG. 24  is a schematic diagram showing communications between an electronic lock on a vending machine and an electronic key during an unlocking process similar to that  FIG. 23  but with a step of checking the lock ID for access control; 
         FIG. 25  is a schematic diagram showing a computer used to program operational limitations into an electronic key; 
         FIG. 26  is a schematic diagram showing the downloading of audit data from vending machines to an electronic key; 
         FIG. 27  is a schematic diagram showing an example of audit data uploaded from a vending machine to an electronic key; 
         FIG. 28  is a flowchart showing the key code learning process of an embodiment of the electronic lock; 
         FIG. 29  is a flowchart showing an operation by an embodiment of the electronic key to back up the time and date for restoring the clock of the key in case of a faulty or removed battery; 
         FIG. 30  is a flow chart showing an operation by the electronic key to record the number of power-up of the key to prevent tampering by battery removal; 
         FIG. 31  is a schematic block diagram showing an embodiment of a vending machine that has a communication device that is interfaced to the electronic lock and in wireless communications with a home base for access control and auditing purposes; 
         FIG. 32  is a schematic diagram showing vending machines accessible by an electronic key that has a narrow wireless signal transmission pattern to avoid accidental opening of the vending machines; 
         FIG. 33  is a functional block diagram showing an embodiment of an electronic access control device having two microprocessors communicating with each other and wherein the device wirelessly communicates with an electronic key; 
         FIG. 34  is a schematic diagram showing a system in which alternative programming schemes for programming the lock of a vending machine in the field may be implemented without requiring the vending machine to be opened before programming; 
         FIG. 35  is a schematic diagram showing data stored in the components in the system of  FIG. 34 ; 
         FIG. 36  is a schematic diagram showing an embodiment in which a hand-held program unit is used to program the electronic lock of a vending machine; 
         FIG. 37  is a schematic diagram showing an alternative embodiment that also uses a hand-held program unit to program the electronic lock of a vending machine; 
         FIG. 38  is a schematic diagram showing another alternative embodiment in which an external computing device is used to remotely program the electronic lock of a vending machine and an electronic key is then used to access the lock; 
         FIG. 39  is a schematic representation of an embodiment of a key management system including a personal computer having a local database and software program, and cradle that functions as an interface for communications between an electronic key and the computer; 
         FIGS. 40A and 40B  are schematic diagrams showing the user interface screen and process for registering the software and the cradle of the key management system; 
         FIGS. 41A ,  41 B and  41 C are schematic diagrams describing a start-up and refresh sequence of the keys; 
         FIG. 42A  is a schematic diagram showing user interface screens for a user to entering supervisor and administrator modes; 
         FIG. 42B  is a flow chart showing a process for a user to enter electronic lock information; 
         FIG. 43A  is a flow chart for a process of starting up or logging in new keys; 
         FIG. 43B  is a schematic diagram showing user interface screens for the operation of entering key user information; 
         FIG. 44A  is a schematic diagram showing a process of collecting electronic lock ID information; 
         FIG. 44B  is a schematic diagram showing user interface screens for prompting a user of the key management system to enter information regarding a new electronic lock; 
         FIG. 44C  is a schematic diagram showing an alternative process for collecting electronic lock ID information; 
         FIG. 45  is a flow chart describing a process of receiving and storing audit data; 
         FIG. 46  is a schematic diagram showing user interface screens for displaying audit trails data collected by electronic keys from vending machines; 
         FIGS. 47A and 47B  are schematic diagrams showing user interface screens for a process of editing key limit operational parameters; 
         FIG. 47C  is a flow chart showing a process of editing key limit parameters; 
         FIG. 48  is a flow chart showing a process of re-calculating key limit parameters during a key refresh operation; 
         FIG. 49  is a flow chart showing a process of refreshing the memory of an electronic key; 
         FIG. 50  is a schematic diagram showing a configuration of multiple key management databases that are synchronized using export files; 
         FIG. 51  is a schematic diagram showing a configuration with multiple key management stations connected via a network to a central key management database; 
         FIG. 52A  is a schematic diagram showing a configuration of multiple key management stations connected to a central database with a database server; 
         FIG. 52B  is a schematic diagram showing a configuration of key management stations at multiple remote separate locations connected to a central database server with multiple databases for the separate locations; 
         FIG. 53  is a schematic diagram showing a configuration with key management stations at different locations connected to a central database server through the Internet; 
         FIG. 54  shows user interface screens for generating an export file for synchronizing distributed databases; 
         FIG. 55  shows a user interface screen for setting software auto-exit and archive settings; 
         FIGS. 56-58  show user interface screens involved in scheduling the operation of the key management system for auto start up; 
         FIGS. 59 and 60  show user interface screens involved in setting the auto-exit time for the key management system; 
         FIG. 61  is a schematic diagram showing in functional blocks an electronic key that has a position sensing component for detecting the locating of the electronic key during field operation; 
         FIG. 62  is schematic diagram showing an appliance in the form of a fountain drink dispenser that is to be enabled using a mobile control device such as an electronic key; 
         FIG. 63  is a data flow diagram showing a secured communication process between a controller of the appliance and the key for enabling the operation of the appliance; 
         FIG. 64  is a data flow diagram showing an alternative communication process between the appliance controller and the key; 
         FIG. 65  is a functional block diagram showing the components of the appliance controller; 
         FIG. 66  is a flow diagram showing a process performed by the appliance controller for controlling the operation of the appliance; 
         FIG. 67  is a schematic diagram showing an embodiment with an appliance in the form of a cooler; 
         FIG. 68  is a schematic diagram showing an embodiment in which a field device being controlled is in the form of a secured container; 
         FIG. 69  is a schematic diagram showing an embodiment in which a field device being controlled is a power tool; 
         FIG. 70  is a schematic diagram showing an alternative embodiment in which location data recorded by a location sensing device are combined with access/control event records stored in a mobile control device; and 
         FIG. 71  is a schematic diagram showing a location sensing device, such as a GPS receiver, received in a cradle in a transportation vehicle. 
     
    
    
     While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments hereof have been shown in the drawings and will be described below. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In an embodiment, an electronic system and method is provided for controlling access of devices. For instance, some devices operating in the field are in a relatively unsecured environment, and it is necessary to control the access or usage of the devices so that they are not accessed by unauthorized persons or that they are not used at unauthorized times or places. The devices that may be advantageously controlled using the system and method of the invention include, for example, safes, appliance devices such as vending machines, coolers, fountain drink dispensers, etc., power tools used in construction sites, shipping containers, and many other types of devices. It will be appreciated that the above list is meant only to provide some examples and is by no means intended to limit the applicability of the invention. 
     Referring to the drawings, there is shown in  FIG. 1  an illustrative electronic access control device  10  having a keypad  11 , light emitting diodes (LEDs)  12  and  13 , and a mechanical lever arm  14 . In this illustration, the device is used as a lock for an office safe. The device can also be applied to various applications including locks for vending machines or amusement games. 
     The main components of the electronic access code device are shown in  FIG. 2  which include a keypad  11 , a microprocessor  14 , an access code input and output  15 , an acoustic output (a piezo ceramic bender, Model No. KB1-1541)  16 , LEDs  12  and  13 , a voltage regulator (LM2936Z-5.0)  17 , a battery  18 , an electromechanical driver output  19 , an oscillator  20 , and a reset circuit  21 . Inputs to the device may take the form of a thumbprint scan, a retinal scan, or a magnetic strip input which may work in conjunction with a keypad or as a sole means of input. Outputs may take the form of an alpha-numeric display which may work in conjunction with an acoustic output or an LED or as a sole means of output. 
     The manufacturers which provide microprocessors applicable to the device include: Micro-Chip (PIC 16C54, PIC 16C57, PIC 16C71, PIC 16C76); Motorola (MC68HC705J1, MC68HC705K1, MC69HC705P6, MC68HC705P8, MC68HC705P9); National Semiconductor (COP 820C); SGS-Thomson (ST 6210); Texas Instruments (370C311); Zilog (Z84C01). 
     A more detailed schematic of the device is shown in  FIG. 3 , highlighting the reduced pin configuration and the serial access to the electrically programmable read only memory (EPROM)  22 . Several of the pins on the microprocessor  14  are multiplexed and perform multiple functions, at times used as inputs and at times used as outputs; thereby, the pin configuration is able to use only 9 pins for the keypad input, the acoustic output, and the EPROM  22  reading and writing. For example, the 12 keypad entries are shown in rows and columns. Each keypad entry in a row is connected to the corresponding pin. For example, keypads “3”, “6”, and “9” are connected to pin R 1 . Each keypad entry in the same column is connected to a corresponding pin as well. For example, keys “3”, “0”, “1”, and “2” are all connected to pin C 3 . 
     The multiplexing of the keypad allows for input of twelve different inputs (“0” through “9”, PROG, and CLR) using a four by three configuration, as shown in  FIG. 4  and  FIG. 5 . In particular, there are four rows and three columns in this configuration. In accordance with another embodiment, a keypad with four different inputs allows for as little as a two by two configuration through multiplexing the inputs. 
     The following example will illustrate the multiplexing with respect to the keypad  11 . Normally, in sleep mode, pins R 1 , R 2 , R 3  and R 4  are waiting for an input. When, for example, the keypad “3” is input, pin R 1 , which keypad “3” is connected to, is triggered signifying to the microprocessor  14  that an interrupt has occurred. The microprocessor  14  then executes an interrupt in the software program and changes one of the four pins (R 1 , R 2 , R 3  and R 4 ) into an output whereby a logic high is sent to the R 1  pin. When a keypad is pressed, it acts as a short circuit; thus, when the microprocessor  14  sends out a logic high, it then senses pins C 1 , C 2  and C 3  to determine exactly which keypad in the row has been pressed. In this case, where keypad “3” is input, C 3  is high. Pressing keypad “3” acts as a short circuit so that when R 1  is sent high, there is a direct electrical connection between pin R 1  and C 3  via keypad “3”. Thus, the microprocessor  14  can determine that keypad “3” was pressed based on R 1  and C 3  both being logic high. 
     Another example of using multiple functions as connected to a single pin is the acoustic output  16 . The acoustic output  16  is connected, via a transistor, to pin C 2 . Pin C 2  is also connected to keypads “CLR”, “4”, “5”, and “6”. When the microprocessor  14  sends an audible signal output, pin C 2  acts as an output. When the microprocessor is sensing the keypad input, C 2  acts as an input. 
     A further example of multiple functions as connected to a single pin is the EPROM  22  sensing function. The EPROM  22 , as shown in  FIG. 3 , is part of the microprocessor  14 . The DATA line (bidirectional in that the line is able to input data to write and output data to read) and CLOCK line of the EPROM  22  are connected to C 1  and C 2 , respectively. Pins C 1  and C 2  are connected to the keypad as well. When the PROGRAM signal is input, C 1  and C 2  function. as inputs when writing to the memory location in the EPROM and function as outputs when reading from the memory location in the EPROM  22 . Through this arrangement, the manufacturer may serially program the device with the access code. The microprocessor  14  uses registers  56  to transmit the incoming serial data into parallel data for the EPROM  22  to input. Further, the end user may read the EPROM  22  access code serially as well. In reading the EPROM  22 , only three pins must be accessed (PROGRAM, DATA, and GROUND). The microprocessor  14  uses registers  56  to transmit the outgoing parallel data from the EPROM  22  to serial form for output. 
     It will be appreciated that by installing a communication port, namely the access code I/O  15 , in the microprocessor-based control circuit, the manufacturer of the device can access the EPROM by interacting with the microprocessor  14  via the communication port. By virtue of this arrangement, the manufacturer can program the access code into the EPROM as the last step in the manufacturing process, i.e., after the control circuit has been fully assembled. Thus, there is no longer the need to use a EPROM that is pre-programmed with access codes, or to attempt to input the access code into the EPROM by means of pin clips or the like during the manufacturing process. This ability to program the EPROM after the completion of the control circuit imparts significant flexibility, efficiency, and reliability to the manufacturing process. 
     The operation of the electronic access code device is shown in flowchart form in  FIG. 4  and  FIG. 5 .  FIG. 4  shows the initialization sequence of the device upon power-up  24 . The microprocessor, which contains an EPROM  22  and a random access memory (RAM)  23 , checks to see if there is an access code stored  25  in the EPROM  22 . The microprocessor  14  performs this operation by checking if a proprietary bit sequence is set, wherein the particular sequence of bits signifies that the EPROM  22  has a stored access code. If the bit sequence is present, the EPROM  22  contains the access code, whereby the microprocessor  14  waits for input from the keypad or waits for an external read signal  26  from the microprocessor  14 . 
     If the bit sequence is not present, the EPROM  22  does not contain the access code in its memory. The microprocessor  14  must then wait for the external program signal  28  which signifies that the access code is being written to the EPROM  22 . The external program signal, as shown in  FIG. 3 , is labeled PROGRAM and is connected to pin  104  and pin IRQ of the microprocessor  14 . In this mode, when the PROGRAM signal is toggled, this signifies that the access code is being burned into the EPROM  22 . The microprocessor  14  then uses the CLOCK and DATA lines to clock in the data thereby reading the access code. Then, the microprocessor  14  stores the access code into memory  30 . The microprocessor  14  subsequently sets the proprietary bit sequence on the EPROM  22  signifying that the EPROM  22  contains the access code. Finally, the microprocessor  14  waits for input from the keypad or waits for an external read signal  26  from the microprocessor  14 . 
     The EPROM  22  can also be used to store features other than the access code. It can be used to determine such things as: (1) the amount of time the solenoid  31  is to be energized upon opening the lock; (2) the number of key presses in the access code; (3) the option of disabling the permanent access code temporarily when a new-access code is stored in RAM  23 ; (4) the device serial number; and (5) the date and time the device was manufactured or put in service. These features allow the manufacturer to deliver to an original equipment manufacturer (OEM) customer a generic electronic lock assembly. The OEM customer may then characterize all the specific lock features at the OEM customer facility. 
     As shown in  FIG. 5 , after the power-up initialization routine, the microprocessor waits for an entry from the keypad  32 . Several functions are available based on the keypad entry. If the program key (PROG key) is first pressed, the operator wishes to input an additional access code  33 . In this mode, the microprocessor  14  inputs the next five numbers from the keypad  34 ,  35 ,  36 ,  37 , and  38 . The comparator  57 , within the microprocessor  14 , compares the two numbers and checks if the input number matches the access code  39  from the EPROM  22  which is stored in RAM  23 . If the two numbers match, this signifies that the operator knows the access code in the EPROM  22  and therefore has clearance to input an additional access code  40 . Thus, the microprocessor accepts the next five numbers from the keypad as the additional access code  41 ,  42 ,  43 ,  44 , and  45 , and stores the new access code  46  in RAM  23 . The operator may then input either the access code from the EPROM  22  or the additional access code to open the lock. The operator may repeat this procedure and place additional access codes into RAM  23 . The additional access codes will be stored in RAM  23  until the power is removed from the microprocessor  14  at which time the RAM  23  memory will be lost. 
     An alternate mode of using the PROG key is to disable the permanent access code in the EPROM  22  temporarily when a new access code is entered into RAM  23 . After the PROG key is hit, the microprocessor  14  inputs the next five numbers  34 ,  35 ,  36 ,  37  and  38 . The comparator  57 , within the microprocessor  14 , compares the input number with the permanent access code  39  from EPROM  22 . If the two numbers match, the microprocessor  14  inputs a second access code  41 ,  42 ,  43 ,  44 ,  45 . In this alternative, when the microprocessor  14  stores in RAM  23  the new access code  46 , it disables access to the permanent access code in RAM  23 . Therefore, until the battery  18  is turned off, the only access code available is the new access code stored in RAM  23 . 
     If an operator enters the PROG key at any time other than at the first keypad entry from sleep mode, the microprocessor will display the error message  47  by sounding the acoustic output  16  through pin C 2  and the LED  13 . 
     If a number from the keypad  11  is first entered while in sleep mode  48 , the microprocessor  14  waits until another four numbers are entered  49 ,  50 ,  51 , and  52 , from the keypad  11 . The microprocessor  14  then compares the number entered from the keypad  11  with the access code  53  stored in RAM  23 . If the numbers match, the microprocessor  14  energizes the solenoid  31  at the output  54 . The microprocessor  14  can also energize a DC motor, an electromechanical relay, or a solid-state relay. If the numbers do not match, the error message is sent  47  by sounding the acoustic output at pin C 2 . 
     If the clear key on the keypad is entered at any time in the operation of the device, the microprocessor  14  waits 5 seconds before going back into sleep mode and waiting for the next keypad entry. 
     One feature of the device is a lockout of keypad operations. If the microprocessor  14  receives three consecutive operations which generate error messages  47 , the microprocessor  14  will disable operation of the device for two minutes. Any attempt to operate the device in the two minute lockout period will generate an error message  47 . 
     An additional feature of the system is a requirement that a digit must be entered within a specified time. Otherwise, the microprocessor  14  will send an error message  47  if there is a five second lapse between keypad entries. 
     A further feature of the system is the modulated voltage across the solenoid  31 . When the correct access code is input  53  from the keypad  11 , the microprocessor  14  energizes the solenoid  31 . The microprocessor  14  must supply sufficient power to the solenoid to unlock the lock (i.e., the solenoid must push the plunger in against the coil to open the lock). This involves two different operations. First, the solenoid  31  must physically push the plunger against the coil. Second, the solenoid  31  must keep the plunger pushed against the coil for the specified time in which to keep the lock unlocked. 
     The first operation (pushing the plunger) is very energy intensive. The solenoid  31  must exert kinetic and potential energy to physically move the plunger against the coil. The second operation (maintaining the position of the plunger) is less energy intensive. The solenoid  31  must exert only potential energy in terms of keeping the plunger compressed against the coil. The device, in order to unlock the lock, supplies the entire battery power necessary for the solenoid  31  to pull the plunger in against the coil. The microprocessor  14  accesses the timer  55 , within the microprocessor  14 , whereby the timer indicates when to reduce the power. Once the plunger is pulled in, the microprocessor  14  modulates the voltage to the solenoid  31 . This reduces the current into the solenoid while the solenoid plunger is held in since the entire DC current is not required to keep the plunger in the closed position relative to the coil. This in turn reduces the total amp-hours of current out of the battery during an access cycle, and the total number of accesses to the device increases. 
     By way of example, the solenoid  31  requires 300 milliamps of current to pull the plunger in. The microprocessor  14  accesses the timer  55 , waiting 0.5 seconds to do that operation. The microprocessor  14  then drops the solenoid current to 150 milliamps. This current is sufficient for the solenoid  31  to keep the plunger flush against the coil. The microprocessor  14  accesses the timer  55  again, waiting for the timer  55  to indicate that three seconds have passed, supplying the lower current to allow the user to open the door. In this manner, the microprocessor  14  uses approximately ½ as much power in the modulated mode. 
       FIG. 6  highlights another aspect of the invention, the remote operation of the electronic access code device using a battery. The device can be integrated with other electronic devices forming a system of electronic locks. At the center of the system is a central control station whereby each of the devices may be accessed. 
     The accessed device is designed for low power consumption so that it may operate on a battery for an extended period of time. The remote access device is normally in a sleep mode. In other words, the device is not in active operation. The remote device can “wake-up” from the low power sleep mode in a variety of ways. One method is for the circuitry in the sleep mode device to sense the incoming signal. When the signal is sent, the remote device resumes normal operation. Another method is for the circuitry in the sleep mode device periodically to resume normal operation and sense if there is an incoming signal. If the incoming signal is sent, the circuitry is able to receive the bitstream data that contains the access code. The circuitry thus remains in a low-power sleep-mode condition for the majority of the time, dissipating low power, while no signal is received. The device may then be powered by a battery. 
     The remote electronic access code device is divided into two parts: the input electronics  60  and the processing electronics  64 . The processing electronics  64  contains a microprocessor, an access code input and output, an acoustic output, light emitting diodes (LED), a voltage regulator, and an electromechanical driver output. Thus, the remote device is similar to the microprocessor in processing the input access code, as shown in  FIG. 1 , except the access code may be input in several ways. In this embodiment, the data stream is input serially into the microprocessor  14  so that a variety of serial inputs may be connected to the input of the microprocessor  14 . For example, the access code may be input using a traditional keypad  11  transmitting data in serial mode. Moreover, the data may be input serially using an electromagnetic signal input from the radio frequency (RF), optical frequency or infrared frequency bands. Thus, the microprocessor  14 , in this configuration, may accept the input from any one of these inputs. 
     The input electronics  60  accepts the code sent from the central control. The method of transmitting the code may take several forms including an electromagnetic signal (such as a RF signal sent by an RF serial bitstream transmitter, or an infrared signal) or a data line (telephone line). 
     When an RF signal is used, the central station transmits a signal via a transmit antenna  63  (transducer that sends radiated electromagnetic fields into space). The radiated waves containing the RF signal contains the bitstream access code which is sent to the input electronics  60 . The input electronics  60  contains the RF wake-up  61  and the RF decode circuitry  62 . In one embodiment, the RF wake-up circuit  61  is ordinarily in a low power sleep-mode. However, for a 10 millisecond period every 1 second, the RF wake-up circuit  61  senses for an RF bitstream signal. If an RF bitstream signal exists, it remains awake and receives the entire RF bitstream signal. The RF wake-up circuit  61  then sends a wake-up enable signal to the RF decode circuit  62 . The RF decode circuit  62 , via the antenna  63 , translates it into a series of bits and then sends the digital bitstream signal to the processing electronics  65  to determine if the digital bitstream signal contains the access code. 
     In another embodiment, the RF wake-up circuit  61  remains in low power sleep mode until it senses the RF signal. The RF signal, in this embodiment, contains a low carrier frequency way and a high frequency RF bitstream superimposed on the low frequency carrier wave. When the RF wake-up circuit  61  senses, via the antenna  66 , that there is a signal tuned to the low frequency carrier Wave, the RF wake-up circuit  61  sends a wake-up enable signal to the RF decode circuit  62 . The RF decode circuit  62  then accepts the RF bitstream access code signal, and translates it into a series of bits for the microprocessor  14 . 
       FIG. 7  shows the schematic of the input electronics  60  wherein the RF wake-up circuit  61  periodically wakes up from a low power sleep mode and senses if there is an incoming RF signal. The RF wake-up circuit  61  consists of two low-power CMOS inverter gates, INV 1  and INV 2 , a CMOS transistor Q 3 , resistors, and a capacitor. The two inverters INV 1  and INV 2  are configured in an oscillator configuration in a ratio of 1 to 100. In other words, the oscillator will switch on for 1/100 of a second. At this time, the CMOS transistor Q 3  will turn on and supply the battery power to the RF decode circuitry  62 . The RF decode circuitry  62  will only draw battery power for 1/100 of the time, and thus the battery will last 100 times longer than if the battery were permanently connected to the RF decode circuitry  62 . 
     The RF decode circuitry  62  consists of two bipolar junction transistors Q 1 , Q 2 , two Operational Amplifiers, OP 1  and OP 2 , and resistors, capacitors, inductors and diodes connected to these components. The RF input signal is referred to as an on-off keying of high frequency bursts for set time frames. In the present invention, the frequency is set at 320 MHz. A burst of frequency is detected by the Q 1  and Q 2  transistors with their circuits tuned to the correct frequency (320 MHz in this example). The RF decode circuitry  62  then senses the data bitstream sent in the form of digital  1  data signal and digital  0  dead band of no frequency. Thus, a train of on and off frequency pulses would be received by the antenna, conditioned and amplified by Q 1  and Q 2  of the RF decode circuitry  62 , and converted to bitstream  1  and  0  digital signals by the two operational amplifier signal conditioners OP 1  and OP 2 . 
     Typically, the operator of the control unit  59  which contains the RF transmitter will enable the RF transmitter with a transmit button  58  to send an RF on-off keying pulse for approximately one second. The RF signal being transmitted is a digital bitstream conditioned to an RF on-off keying signal which takes about two milliseconds in which to transmit one complete signal. The control unit  59  then repeats the signal over and over for the duration that the RF transmitter is enabled. In order for the receiver to detect one complete bitstream from the transmitter, the RF signal only needs to be sampled for two milliseconds during which the transmitter is enabled and transmitting. If the RF transmitter is enabled for one second, the transmitted bitstream signal takes 1/500 of a second to be transmitted and is repeated 500 times over the entire one second. The receiver is enabled for 1/100 of a second every second, and will have the opportunity to sample and detect a signal that is 1/500 of a second in duration, transmitted 500 times over one second. After the 1/100 of a second, the oscillator, formed by INV 1  and INV 2 , will switch Q 3  off, and the battery power to the RF decode circuitry will be shut off. Only the oscillator circuit (INV 1  and INV 2 ) will dissipate battery power at a small rate of less than 100 micro-amps. 
     If less power dissipation by the RF decode circuitry  62  is required, the decode circuitry power duty cycle can be reduced by increasing the oscillator frequency to more than 100 to 1 and thus decreasing the RF decode circuitry  62  sample rate. In order to ensure the RF decode circuitry  62  will be enabled long enough to detect the entire transmitter digital bitstream, the lock CPU would wait for the beginning of the bitstream signal which is received by the RF decode circuitry  62  when the circuitry was enabled and conditioned through OP  1 , and then would send an output enable signal back to Q 3  to override the oscillator and keep the RF decode circuitry  62  enabled with battery power until the lock. CPU has received the correct amount of bitstream data from the transmitter through the decode circuitry. Thereafter, the lock CPU would disable the Q 3  transistor and the RF decode circuitry and let the oscillator go back to its low rate of sampling. 
     The processing electronics  64  remains in sleep-mode low current operation until a valid on-off keying frequency signal is received while the RF decode circuitry is enabled and a digital bitstream signal is sent to the lock microprocessor  65 . Upon transferring the bitstream signal, the microprocessor  14 , within the processing electronics, compares the input code with the access code in the comparator. If correct, the solenoid, DC motor, electromechanical relay, or solid-state relay is activated. After this operation, the microprocessor  14  sends a disable signal to the RF wake-up circuit to assume a low power mode. 
       FIG. 8  shows the schematic of another embodiment of the electronic access control device which also multiplexes the inputs and outputs of the pins of the microprocessor to reduce the number of pins required. The microprocessor  81  used in this embodiment is preferably the MC68HRC705J1A integrated circuit (IC) manufactured by Motorola. As illustrated in  FIG. 8 , the input devices include a keypad  11  and an electronic key reader  82 . 
     In this embodiment, instead of using an EPROM internal of the microprocessor as in the case of the embodiment of  FIG. 3 , an EEPROM  84  external of the microprocessor  81  is used to store the programmed access code as well as other useful information. The EEPROM  84  used in this embodiment is preferably the 93LC46 IC manufactured by Microchip. Alternatively, a FLASH read-write memory, or any other type of suitable memory, may be used. To effectively use the limited number of pins of the microprocessor  81 , the pins are multiplexed such that the keypad  11  and the EEPROM  84  share several communication pins. As illustrated in  FIG. 8 , pins  16  (PA 2 ),  17 (PA 1 ),  18  (PA 0 ) of the microprocessor  81  are connected to pins  4 ,  3 , and  2  of the EEPROM  84 , respectively. These pins of the microprocessor  81  are also connected to the keypad  11  for receiving access codes entered by means of the keypad. Pin  3  (PB 5 ) of the microprocessor  81  is connected to pin  1  of the EEPROM. In this configuration, pins  1 - 4  of the EEPROM  84  are used, respectively, for chip select, data in, data out, and clock. 
     In accordance with an aspect of the present invention, the microprocessor-based control circuit further includes a low-battery detection circuit  68  that does not consume electrical power except when a low-battery detection is in progress. As illustrated in  FIG. 8 , the access control device is powered by a battery pack  70  which includes one or more batteries. The output of battery pack is connected to a voltage regulator  72  which provides a regulated voltage for operating the control circuit. The low-voltage detection circuit  68  includes a voltage divider  74  which has its input end connected to the output of the battery pack  70  (which in the illustrated case is after an isolating diode  71 ). The voltage divider  74  is connected in series with a transistor  76  to ground. The base of the transistor  76  is connected (via a resister  77 ) to pin  6  (PB 2 ) of the microprocessor  81 . When Pin  6  of the microprocessor  81  is set high, the transistor  76  is turned on, thereby allowing current to flow through the voltage divider  74 . When pin  6  is set low, the transistor  76  is turned off, and the current through the voltage divider is cut off. In that case, the output voltage of the voltage divider  74  will be pulled up to that of the battery voltage minus the voltage drop across the diode  71 . 
     The output end of voltage divider  74  is connected to the base of a second transistor  80 . The input end of the transistor  80  is connected to the output of the voltage regulator  72 , while the output end of the transistor  80  is connected to pin  15  (PA 3 ) of the microprocessor  81 . Normally pin  6  of the microprocessor would stay low, and both the transistor  76  and the transistor  80  would be turned off. When a battery voltage test is performed, pin  6  is switched to the high (“1”) state to turn on the transistor  76 , and the state of pin  15  is sensed by the microprocessor  81  to determine the on/off state of the transistor  80 . If the battery voltage is sufficiently high, the output of the voltage divider  74  would be high enough to turn the transistor  80  off. On the other hand, if the battery voltage is low, the output of the voltage divider would be low enough to turn the transistor  80  on, and pin  15  would be switched to the high state. 
     In accordance with an important aspect of the present invention, there is provided an electronic access control device that provides substantially enhanced security and reduced vulnerability to tampering by using two microprocessors.  FIG. 9  shows generally the functional block diagram of such a device. As illustrated in  FIG. 9 , the control device has a first microprocessor  90  and a second microprocessor  92 . The first microprocessor  90  is connected to an input device  94  for receiving a user-entered control signal signifying a demand to operate an electronic device  98 . The second microprocessor  92  controls a driver circuit  96  for energizing the electrical device  98  to effect a desired operation. The electrical device  98  may be, for example, a solenoid, motor, relay, or the like for opening a lock, or, as will be described in greater detail below, the ignition relay of a motorcycle. The first microprocessor  90  may be positioned close to the input device  94 , while the second microprocessor  92  may be located close to the electrical device  98  and is preferably well shielded from external access. The two microprocessors are connected by a two-way communication link  100 . 
     As will be described in greater detail below, the user-entered control signal may be, for example, an access code entered using a keypad or electronic key, the operation of an electronic ignition switch controlled by a mechanical lock, or a voice command entered through a voice sensor such as a microphone. Once a user-entered control signal is received, the first microprocessor  90  determines whether the demand to operate the electrical device  98  should be transmitted to the second microprocessor  92 . If the demand is to be transmitted, the first microprocessor  90  sends a special communication code to the second microprocessor  92  via the communication link  100 . The second microprocessor  92  compares the transmitted communication code with a preset communication code stored in a non-volatile memory  102 . If the transmitted code matches the stored code, the second microprocessor  92  activates the driver circuit  96  to energize the electrical device  98 . 
     It will be appreciated that this dual-microprocessor configuration significantly reduces the vulnerability of the device to tampering. Even if a tamperer may gain access to the first microprocessor, it is intended that the second microprocessor is well shielded and therefore cannot be reached easily. Since the second microprocessor responses only to a correct communication code, the tamperer will not be able to use the trick of “hot-wiring” to activate the driver circuit  96 . 
     Moreover, even if the circuit containing the first microprocessor is somehow replaced by another similar microprocessor circuit for which the correct control signal is already known, that new microprocessor is unlikely to know the communication code specific to the second microprocessor  92 . In this way, the two microprocessors function as two individual gate keepers. Even if the first microprocessor could be somehow bypassed, the second microprocessor would not activate the driver circuit without receiving the correct communication code. 
     The microprocessors can also be programmed to implement the “code-hopping” or “rolling-code” scheme used in some existing electronic access control devices to further improve the security of the device. In such a scheme, the preset code stored in the non-volatile memory  102  is used as a seed, and the communication codes stored in the first and second microprocessors are changed as a function of the number of code transmission according to a predefined algorithm based on the seed code. The changes of the communication codes in the two microprocessors are synchronized so that they remain in operative relationship. 
       FIGS. 10A and 10B  illustrate an application of the dual-microprocessor configuration in an electronic lock. In this embodiment, the control circuit has two halves connected by a cable. The first half, which is shown in  FIG. 10A , contains a first microprocessor  110 . The second half, shown in  FIG. 10B , contains a second microprocessor  112 . Pin  11  (PA 7 ) of the first microprocessor  110  is connected to pin  18  (PA 0 ) of the second microprocessor  112  via the cable  115  and the mating connectors  114  and  116  to establish a two-way serial communication channel between the two microprocessors. 
     The electronic lock has a keypad  11  and an electronic key reader  82  as input devices which are connected to the first microprocessor  110 . The second microprocessor  112  controls a energizing circuit  118  for energizing a solenoid  120  to open the lock. When the first microprocessor  110  receives an access code via either the keypad  11  or the key reader  82 , it compares the entered access code with an access code stored in its memory. If the entered code matches the stored access code, the first microprocessor  110  transmits a communication code to the second microprocessor  112  via the communication channel described above. The second microprocessor  112  then compares the received communication code with a preset communication code stored in an EEPROM  122 . If the two communication codes match, the second microprocessor  112  activates the energizing circuit  118  to energize the solenoid  120  to open the lock. 
     The correct access code and communication code are preferably stored in the EEPROM  122 . During initial power-up, i.e., when the battery is first attached to the electronic lock, the second microprocessor  112  transmits the access code and the communication code to the first microprocessor  110 , which then stores the codes in its memory (which may be volatile) for subsequent operation. 
     The dual-microprocessor configuration illustrated in  FIG. 9  can also be advantageously used in other types of applications. For example,  FIG. 11  shows an electronic ignition control system for a motorcycle. In this embodiment, the device contains a first microprocessor  126  and a second microprocessor  128  which are connected by a cable  130 . A three-position ignition switch  132  is connected to the first microprocessor  126 , which may be located close to the ignition switch. The second microprocessor  128  is connected to an ignition relay  134  and an accessory relay  138 , and is preferably disposed close to the ignition mechanism of the motorcycle and well protected from external access. 
     In this arrangement, the ignition switch  132  serves as the input device, and the position of the ignition switch is used as the user-entered control signal. The first microprocessor  126  monitors the switch position. When the ignition switch  132  is turned to the “accessory” position  135 , the first microprocessor  126  transmits a communication code together with a switch-position code corresponding to that switch position to the second microprocessor  128 . The second microprocessor  128  compares the transmitted communication code with a preset communication code stored in a non-volatile memory  138  which has been programmed at the factory. If the two codes match, the second microprocessor  128  determines from the switch-position code that the switch is set at the accessory position and closes the accessory relay  136 . 
     Similarly, when the ignition switch  132  is turned to the “ignition” position  133 , the first microprocessor  126  transmits a communication code and a switch-position code corresponding to the ignition position to the second microprocessor  128 . The second microprocessor  128  compares the transmitted communication code with the preset communication code. If the two codes match, the second microprocessor  128  determines from the switch-position code that the switch is set at the ignition position and accordingly closes the ignition relay  134  and the accessory relay  136  to start the engine. 
     It will be appreciated that due to this dual-microprocessor arrangement, this ignition control system cannot be “hot-wired” to start the engine of the motorcycle like conventional motorcycle ignition control systems. This system is also not susceptible to tampering by replacing the assembly of the ignition switch  132  and the first microprocessor  126  with another such assembly for which an ignition key has been obtained. 
       FIGS. 12-14  show another advantageous application of the dual-microprocessor configuration of  FIG. 9  which utilizes speech recognition to control the operation of an electronic access control device. As illustrated in  FIG. 12 , the access control device uses a speech recognition microcomputer integrated circuit (IC)  1200  to process voice commands given by a user. The speech recognition IC  1200  is capable of not only recognizing the commands given but also the voice of the speaker. In other words, the IC is capable of speaker dependent recognition, allowing the user to customize the words to be recognized. Such an IC may be, for example, the RSC-164 microcomputer of Sentry Circuits, Inc. 
     In the embodiment shown in  FIG. 12 , the speech recognition IC  1200  has a microphone  1202  connected thereto for receiving voice commands from a user. In this embodiment, the combination of the voice recognition IC  1200  and the microphone  1202  serves generally the function of the input device  94  of  FIG. 9 . An optional keypad  11  may also be used for entering an access code. After receiving a voice command, the speech recognition IC  1200  analyzes the voice command to recognize the command and the voice pattern of the speaker. If the voice recognition IC  1200  recognizes the voice pattern to be that of an authorized user, it transmits a command code corresponding to the command received to the first microprocessor  190 . The first microprocessor  190  transmits an operation code corresponding to the command and a communication code stored in its memory to the second microprocessor  192  via a bidirectional communication link  180 . The second microprocessor  192  compares the transmitted communication code with a preset communication code which is stored in a non-volatile memory  194 . If the two communication codes match, the second microprocessor  192  activates the driver circuit  196  to energize an electrical device  198  to carry out the operation specified by the operation code. 
       FIG. 13  shows another embodiment of the voice controlled access control device. In this embodiment, the voice recognition IC  1200 , which is a microcomputer in itself, is used to serve the function of the first microprocessor  190  of  FIG. 12 . Upon receiving a voice command through the microphone  1202 , the voice recognition IC  1200  recognizes the command and analyzes the voice pattern of the speaker. If the voice recognition IC  1200  determines that the speaker is an authorized user, it transmits an operation code and a communication code stored in its memory  1201  to the second microprocessor  192 . If the transmitted communication code matches a preset communication code, the second microprocessor  192  executes the command by activating the driver circuit  196 . 
       FIG. 14  shows another embodiment of the voice operated access control device which includes a central control station  1220  and one or more remote devices in the arrangement shown generally in  FIG. 6 . The central control station  1220  may be formed as a hand-held remote control unit which can be conveniently carried and handled by the user. For illustration purposes, two remote devices  1212 A,  1212 B are shown, each of which has its own unique identification code. The identification codes are stored in the memories  1216 A,  1216 B of the microprocessors  1228 A,  1228 B of the respective remote devices. The central control station  1220  has a voice recognition IC  1200  coupled to a microphone  1202  for receiving and recognizing a voice command. If the voice pattern of the speaker matches a voice pattern stored in the voice recognition IC  1200 , the voice recognition IC transmits a command code corresponding to the given command to a central microprocessor  1222 . The command code may contain a code to indicate which remote device is to be contacted. Alternatively, the determination of which remote device is to be contacted may be made by the central microprocessor according to the command code provided by the voice recognition IC  1200 . 
     The central microprocessor contains a memory  1224  which has the identification codes for the remote devices stored therein. After receiving the command code, the central microprocessor  1222  sends out through the transmitter circuit  1226  a bitstream signal which contains the identification code of the remote device to be addressed and an operation code indicating the operation to be performed. In the preferred embodiment, the bitstream signal is transmitted at a radio frequency (RF). Other suitable transmission bands may also be used. 
     The remote devices  1212 A,  1212 B preferably are normally in the sleep mode and can wake up in the ways described in conjunction with  FIG. 6 . In the illustrated embodiment, each remote device has a wake-up circuit  1230 A,  1230 B and a radio frequency decode circuit  1232 A,  1232 B. After receiving the bitstream signal from the central control station  1220 , the radio frequency decode circuit of each remote device converts the received RF signal into a computer-compatible binary code which includes the identification code and the operation code. Each remote device then compares the received identification code with its own identification code. If the codes match, the remote device carries out the specified operation. 
     This voice-activated remote access control system finds many applications in different settings. For example, as illustrated in  FIG. 14 , the remote access control device  1212 A is connected to a file cabinet  1240  and a desk  1242  in an office for locking and unlocking the cabinet drawers and desk drawers. By way of example, when the user gives the voice command “lock desk,” the central control station  1220  receives the command through the microphone  1202 . If the speaker&#39;s voice is recognized, the central control station  1220  sends out a bitstream signal to cause the remote unit  1212 A to operate a lock mechanism  1241  in the desk  1240  to lock the desk drawers. As another example illustrated in  FIG. 14 , the remote device  1212 B is used to control a motor  1243  in a tool chest  1244  to lock and unlock the doors and drawers of the tool chest. 
     In accordance with the object of the present invention to prevent the unauthorized use of electronic keys, there is provided an electronic access control system which has a plurality of remote electronic locks and a master key that has a number of access programmed therein. As illustrated in  FIG. 15 , the access control system includes a master control device  140  for programming a master access code and the desired number of access into the master key  142 . In the illustrated embodiment, the master control device  140  is a personal computer which has an interface device  144 , such as a key reader, for communicating with the master key. The master key  142  contains a non-volatile memory which includes an access code storage  146  for storing the master access code specific to the control system, and a counter  148  for storing the number of access allowed. Also shown in  FIG. 15  is an electronic lock  150  which can be opened by the master key. The electronic lock has a control circuit based on a microprocessor  151  and a key reader  152  for communicating with the master key. When the master key  142  is presented to the key reader  152 , the microprocessor  151  of the electronic lock reads the access code stored in the master key and compares that code to a preset master access code stored in its memory. If the two codes match, the control circuit reads the number of access stored in the master key. If the number of access is one or greater, the microprocessor  151  energizes the solenoid  154  to open the lock  156 . In conjunction with the opening of the lock, the microprocessor  151  of the electronic lock  150  decrements the number of access stored in the counter  148  of the master key by one. Thus, if the number of access in the counter  148  is initially set to one, after the opening of the lock the counter is reduced to zero, and the master key cannot be used to open another lock. 
     In this way, by limiting the number of times the master key  142  can be used to open locks, the unauthorized use of the master key is effectively prevented. For instance, in the setting of a hotel, it is necessary to have a mater key for opening the electronic locks installed in the safes in the hotel rooms. If a hotel guest forgets the access code for the safe in his room, the master key can be programmed with the number of access set to one, and used to open that safe. Since the number of access will be reduced to zero after the lock is opened, the master key cannot be subsequently used to open the safe in another room. The use of the master key is thus strictly controlled. 
     In accordance with another aspect of the invention, there is provided an alarm system for a bicycle or a similar manually powered vehicle. As illustrated in  FIG. 15 , this alarm system includes a remote control  160  mounted in the helmet  162  of the rider of the bicycle  166 , and an electronic alarm  164  mounted on the bicycle. The remote control  160  has a transmitter  168  for the wireless transmission of a communication code and other types of control signals to the alarm  164  on the bicycle, which has a receiver  170  for receiving the transmitted signals. 
     In the preferred embodiment, the remote control  160  has a button  172  which when pushed transmits a control signal including the communication code to the alarm  164  on the bicycle to activate or deactivate the alarm. Alternatively, the helmet may be equipped with a keypad for entering an access code by the user. After receiving the access code, the remote control compares the entered access code with a preset access code and transmits the control signals to the electronic alarm on the bicycle when the two access codes match. 
     The alarm  164  includes a motion detector  174  for sensing the movement of the bicycle  166 . If movement of the bicycle is detected by the motion detector  174  when the alarm has been activated, the electronic alarm  164  emits audio and/or visual warning signals to deter the potential theft. A timer  176  is included in the electronic alarm  164  to stop the warning signals after a predetermined amount of time has elapsed. 
     This bicycle alarm system which has a remote control  172  mounted in the riding helmet  162  has many advantages. Combining the remote control with the riding helmet provides significant convenience to the rider because there is no need to carry the remote control separately. Moreover, because the remote control is integrated in the helmet of the rider, the rider is less likely to lose or misplace the remote control. Furthermore, because the remote control is required to deactivate the alarm system, combining the remote control with the helmet provides an incentive for the rider to wear the helmet when riding the bicycle. In this way, the bicycle alarm system of the present invention contributes to the safety of the rider and helps the rider to obey the law requiring the bicycle rider to wear a helmet. 
     With reference to  FIG. 17 , a system and method is disclosed wherein the field devices are vending machines. It will be appreciated that the operative principles of the invention described in connection with this embodiment can be applied to other field devices, as will be described in greater detail below. 
     Moreover, as will become clear from the following description, the embodiment of the invention implemented for use with vending machines provides significantly improved security and ease of management over conventional vending machines equipped with mechanical locks. The term “vending machine” as used herein means a device that performs a money transaction, which may involve the insertion of cash or commercial paper, or the swiping of a credit and/or debit card, and may (but not required to) dispense an item or items or provide functions in response to the money transaction. In this regard, this term is meant to cover broadly machines commonly used for vending drinks and snacks, ATM stations, change machines, toll machines, coin-operated laundry machines, video arcades, etc.  FIG. 17  shows, as an example, a vending machine  220  with an embodiment of an electronic lock mounted therein. The vending machine  220  has a front panel  222  or door that can be opened when the electronic lock is unlocked with a properly programmed electronic key  226 . It will be appreciated that the vending machine and the electronic key are not shown to scale in FIG.  17 , and the view of the electronic key is significantly enlarged with respect to the vending machine to show its features. 
     The key  226  and the lock preferably communicate with each other wirelessly, which may be via an infrared or radio frequency (RF) channel. In a preferred embodiment, the wireless communications between the key and the lock is via infrared transmissions. The infrared medium is preferred because it is directional and short range, and the infrared circuitry in the lock is not sensitive to the metal cabinet enclosure of the vending machine. Thus the vending machine will less likely be opened accidentally if the key is accidentally operated of if the key is operated to unlock another vending machine nearby. In addition, the infrared light can travel through the selection buttons on the vending machine. This allows the infrared transceiver of the electronic lock to be positioned behind a selection button  230  of the vending machine, as illustrated in  FIG. 17 . To that end, the vending machine  220  has an infrared transceiver disposed to receive infrared transmission through its front panel  222 , and the electronic key  226  has an infrared transceiver at one end  232 . As shown in  FIG. 17 , in one implementation, the electronic key  226  has a very simple profile, having only a “START” button  236  that can be activated by a user for lock opening and key code learning operations. In a preferred embodiment, the “START” button  236  need not be continuously pressed in order for the key to transmit the encrypted code to the lock. Instead, the user only has to only momentarily press the button  236 , and the key will automatically stop transmitting after a few seconds, thus the key will not transmit indefinitely and deplete the battery if the button is stuck down. The electronic key  226  also has a light-emitting diode (LED)  238  exposed through a hole in the housing of the key for indication the operation status of the key. 
     In accordance with an aspect of the invention, the electronic lock assembly is mounted inside the vending machine  220  to prevent unauthorized access and tampering. It can be physically accessed only when it is properly unlocked and the door  222  or front panel of the vending machine is opened. In one embodiment, as shown in  FIG. 18 , the electronic lock assembly  248  is mounted on the inside of the door  222 , and opening the door of the vending machine exposes the lock assembly housing  240 . The electronic lock  248  includes a lock shaft  242  that engages into a corresponding receptacle in the body of the vending machine to prevent the door from being opened when it is in a locked position. The electronic circuit of the lock resides in the housing  240  of the lock assembly. The housing  240  has two holes. Behind one hole  244  is a “LEARN” switch connected to the electronic lock circuit. This switch can be accessed and pressed down with a thin object, such as a screwdriver or a car key. Behind the other hole  246  is a light-emitting diode (LED), which servers as a means for providing an indication of the operational state of the electronic lock during a key code learning operation or a lock opening operation, as will be described in greater detail below. 
     Turning now to  FIG. 19 , in one embodiment, the circuit of the electronic lock  248  comprises a microcomputer  250 , a non-volatile memory  252 , a half-duplex IRDA infrared communication interface  254  for communicating with an electronic key, a power supply voltage regulator  256 , a lock motor or solenoid control circuit  258 , position feedback switches  260 , a learn switch  262  as mentioned above, and the LED  264  for state indication. The non-volatile memory is for storing key codes  268 , encryption codes  270 , and audit data  272 , as will be described in greater detail below. 
     In an alternative embodiment, the vending machine with the electronic lock is to be accessed using a mechanical key rather than an electronic key. To that end, the electronic lock includes an interface to a combination (the “switch-lock” combination) of an electrical switch  274  and a mechanical lock  276  that has a cam for moving the switch into a closed or open position. The electrical switch  274  is normally in an open state and is closed when the mechanical lock  276  is opened using an associated mechanical key  278 . The open/close state of the switch  276  is detected by the microcomputer  250  and is used to determine whether the mechanical lock  276  is opened or closed. The microcomputer  250  is programmed to unlock the door  222  of the vending machine  220  in response to the closing of the switch contact caused by unlocking of the mechanical lock  276  using the mechanical key  278 . Thus, the unlocking process does not involve the passing of a key code between the electronic lock and an electronic key. Accordingly, as described in greater detail below, during a learning process, the electronic lock learns that it is to be accessed using a mechanical key instead of an electronic key with a key code. 
     As shown in  FIG. 20 , in one embodiment, the electronic key  226  includes a microcomputer  280 , a non-volatile memory  282 , a half-duplex IRDA infrared communication interface  284  for communicating with the electronic lock of a vending machine or with a computer for programming the key, a power source (e.g., a battery)  286 , a real-time clock integrated circuit (IC)  294  for generating data indicating the date and time, and the “START” switch  236  and the LED light  238  as mentioned above. The non-volatile memory  282  is for storing a key code  288 , encryption codes  290 , and audit data  292  generated by the key and/or downloaded from vending machines operated using the key, as will be described below. 
     The key codes in the keys and the locks of the vending machines are used to define the security and access control strategy of the electronic lock system. Each electronic key  226  has a key code  288  stored therein, and the same key code is stored in the memory  252  of the electronic lock in each vending machine to be operated with the electronic key. During each access attempt, the key code in the electronic key is transferred from the key to the electronic lock using a secured communication method. The electronic lock can be unlocked if the key code it receives from the electronic key matches the key code stored in the memory of the lock. 
     In one implementation as shown in  FIG. 21A , a key code  268  stored in an electronic key includes seven (7) digits. The first digit of the key code is used to indicate the type of the key. As the value of the key-type digit may go from 0 to 9, there may be up to 10 total key types. As will be described below, in one embodiment of the electronic lock system, there are three different key-types: low-security key, standard key, and auto-tracking key, which correspond to different levels of security in lock-opening operation and audit data collection. The next 6 digits in the key code are the access code (000,000 to 999,999). In addition to the 7 digits representing the key type and access code, a key code stored in the electronic key additionally includes two lower digits, which may be used as the identification (ID) code of that key. In this example, the key ID may vary from 0 to 99. Thus, there may be up to 100 keys that have the same key type and access code but different key ID numbers. 
     Similarly, as shown in  FIG. 21B , a key code  268  stored in the electronic lock has seven (7) digits. The first digit indicates the key type, and the remaining 6 digits are the access code. As mentioned above, there may be up to 10 different key types, and the electronic lock may be programmed to accept a number of key codes of different key types. 
     In accordance with a feature of the invention, the electronic lock  248  of the vending machine  220  is field-programmable. In other words, the key code or key codes of the electronic lock  248  can be programmed (or “learned”) into the non-volatile memory  252  of the lock after the vending machine has been installed in a given location. In a preferred embodiment, the electronic keys to be used to operate the vending machines are programmed with a permanent key code at the factory and ordered by the users of the electronic locks. In the example given above, the users may order up to 100 keys with the same access code. In contrast, the electronic locks to be used in the vending machines are not programmed with any customer-specific key code. Instead, the electronic locks are programmed with a universal code at the factory. The “universal code” is the code put in the lock by the manufacturer of the lock or the vending machine, and is used by the customers to unpack and open the machines after they receive the machines. Thereafter, the electronic locks are installed in the vending machines, which are then shipped to and set up at their respective operating places. In accordance with the invention, the access control strategy is established by “learning” or transferring the access code of the electronic key to be used to operate the machine into the electronic lock via a secured transfer process. 
     Referring back to  FIGS. 17-19  and  28 , in one embodiment, to make the electronic lock  248  learn the access code from an associated electronic key  222  or that it is to be controlled by a switch-lock, the service person has to gain access to the LEARN switch  262  of the lock. In addition, it is preferred that the lock microcomputer senses, using the position switches  260 , that the lock is in the unlocked position to allow entering into the “learn” mode (step  460  in  FIG. 28 ). To that end, if the door  222  of the vending machine is originally closed and the lock contains the universal key code programmed at the factory, the service person uses a key containing the universal key code to unlock the vending machine and open the door to gain access to the LEARN button of the lock. As mentioned above, the LEARN switch  262  should be at a secured location such that it can be accessed only when the lock is properly unlocked (as opposed to a forced entry) and when the door is open. An assumption in the access control strategy is that an authorized person is servicing and/or reprogramming the lock if the door is properly unlocked and opened. If the microcomputer  250  detects (step  462 ) that the LEARN switch  262  is pressed (e.g., held for longer than three seconds), it waits (step  466 ) for the switch to be held in that position for a pre-selected time period (e.g., 3 seconds) and then enters a LEARN process (step  468 ). In response to the pressing of the learn button, the LED  264  is turn on (step  470 ). In alternative embodiments, the LEARN switch  262  can be substituted by another activation means that provides a greater level of security, such as a keypad for entering a service authorization code or an electromechanical switch lock that requires a mechanical or another electronic key. 
     Once the lock  248  is put in the LEARN mode, the service person operates the electronic key  222  containing the desired key code by pressing the button  236  on the key. This causes the key  222  to transmit the key code stored in its memory to the electronic lock. If the electronic key and the lock employ encryption techniques in their communications, the electronic key  222  first encrypts the key code  288  with the encryption codes  290  in its non-volatile memory and then transmits the encrypted code. 
     The service person is given a pre-selected timeout period (e.g., 15 seconds) to press the key to transmit the key code. To that end, the lock  248  determines whether it has received the transmitted key code (step  472 ). If it determines (step  474 ) that a key code transmission is not received within the timeout period, the learning process is terminated. If a key code has been transmitted within the timeout period, the electronic lock  248  receives the transmitted key code via its receiver port  230 . If the transmitted code is encrypted, the electronic lock decrypts the received data with the encryption codes  272  in its memory  252 . In a preferred embodiment, the encryption codes in the electronic key and the electronic lock are inserted during manufacturing at the factory, and different encryption codes may be used for different vending machine owners (e.g., different soft drink bottlers) so the keys given to one owner may not be learned into and used to access the vending machines of another owner. 
     If the encryption codes of the key and the lock do not match, the electronic lock will not be able to successfully decrypt the received key code. In that case, the process will end and the lock will not learn the new key code. If, however, the decryption was successful, the lock stores the key code at a proper location in its non-volatile memory  252  according to its key type (step  476 ). After verifying that the key code is stored correctly in the proper key type location, the lock  248  provides a signal to the service person by flashing the LED  264  to indicate that the LEARN process is successfully completed (step  478 ). From this point forward, the electronic lock will use the newly learned key code for access control. In other words, it will compare this key code with the key code transmitted from an electronic key to determine whether the door should be unlocked. If there was a key code of the same key type previously stored in the memory  252  prior to the LEARN operation, that old key code will be erased and can no longer be used to access the vending machine. 
     As mentioned above, in an alternative embodiment, the vending machine equipped with the electronic lock may be accessed with a mechanical key rather than an electronic key. The electronic lock learns that it is to be controlled by the combination of the electrical switch  274  and the mechanical lock in a learning process similar to the one for learning a key code as described above. Specifically, to enable the lock access via the switch-lock, the service person puts the electronic lock into the learn mode by pressing the LEARN switch  262  as described above. Once the electronic lock  248  is in the learn mode, the service person uses the mechanical key  276  to unlock the mechanical lock  276 . When the mechanical lock  276  is moved to its unlocked position, its cam closes the contact of the electrical switch  274 . The microcomputer  250  of the electronic lock receives the contact-closure signal (i.e., detecting that the electrical switch is closed) and treats the signal as indication that the vending machine is to be accessed using a mechanical key. In response, the microcomputer set its operation mode such that in the future it will unlock the door of the vending machine in response to detecting the closure of the contact of the electrical switch  274 . Thus, from this point forward, the vending machine is accessed using the mechanical key  278 , which replaces one or more types of electronic keys. 
     It will be appreciated that the key learning process described above does not require changing or replacing any physical components of the lock. If the electronic key for operating the lock on the vending machine is stolen or lost, the service person will first use a back-up key that has the key code of the key that is lost, or a key that has a different key code that has been previously learned into the lock, to open the door. The service person then uses the key learning process described above to change the key code in the memory of the lock to a new value. This field-programmability of the electronic lock makes key management significantly easier and cost-effective, and provides a greater level of key security compared to mechanical keys. In contrast, with conventional vending machines using mechanical locks, the mechanical keys may be copied or stolen easily, and the entire lock core of each of the vending machines affected has to be replaced in order to change to a different key. 
     In the illustrated embodiment, one digit in each key code stored in the lock indicates the type of the key, and there may be up to ten different key types. A lock is able to learn one key code for each allowed key type. A key code of a first type may be that learned from a “primary” electronic key for the vending machine, while a key code of a second type may correspond to a different electronic key, such as a “master” key that can be used as a back-up in case the primary key is lost, stolen, broken, or otherwise unavailable. 
     In a preferred embodiment, as briefly mentioned above, different types of electronic keys (indicated by the different values of the key type digit) are provided that correspond to different levels of security (and the associated complexity of communication) and audit data collection function. The three types of electronic keys are economy key, standard key, switch-lock, and auto-tracking key. The operation of each of these three types of keys is described below. 
     Referring to  FIG. 22 , the economy key employs a simple one-way communication process for interacting with a corresponding electronic lock on a vending machine. Since the communication process is simpler and the one-way communication does not require a receiver in the key, the key can be build at a lower cost. As shown in  FIG. 22 , the memory  302  of the economy key contains a key code  304 , an encryption code  306 , and a random number  308 . In a preferred embodiment, the key starts with a given value of the random number, and the random number changes every time the key cycles through a key code transmission. When a user activates the key by pressing the button on the key, the key uses the encryption code to encrypt (step  310 ) the key code  304  together with the random number  308 , and transmits the encrypted number  312  to the electronic lock. When the electronic lock receives the transmitted encrypted data, it decrypts (step  316 ) the data with the encryption code  318  in its memory  252 . The lock then retrieves the key code  322  from the decrypted data and compares it with the key code  320  of the same type in its memory. If the two key codes do not match, the process ends. If they match, the electronic lock proceeds to unlock the door of the vending machine. 
     In comparison with the economy key, the standard key provides a more secure unlocking process that requires 2-way encrypted communications between the key and the electronic lock. The 2-way communications is in the form of a bidirectional challenge-response process. Referring to  FIG. 23 , the memory  330  of the key contains the key code  332 , the encryption code  334 , a real-time clock timestamp  336 , and a random number  338 . Similarly, the memory  252  of the electronic lock of the vending machine contains a learned key code  340 , the encryption code  342 , and an ID  346  of the electronic lock. When the service person presses the transmission button on the electronic key, the electronic key encrypts (step  350 ) the key code  332  in its memory together with the time stamp  336  and the random number  338 , and transmits the encrypted key code and timestamp to the electronic lock of the vending machine. The electronic lock receives the transmitted data  352  through its infrared communication interface and decrypts (step  356 ) the received data with the encryption code  342  in its memory. Next, the electronic lock compares (step  362 ) the decrypted key code  360  with the key code  340  of the same type in its memory. If the two key codes don&#39;t match, the process ends, and the door will not be unlocked. In that case, the electronic lock sends a code to the key to indicate that the key has tried an incorrect key code. 
     If the two key codes match, the process continues and enters a second phase in which the electronic lock transmits data to the electronic key. Specifically, the lock encrypts (step  364 ) the key code, the lock ID  346 , and the random number. It then transmits the encrypted key code, lock ID, and the random number (originally sent by the key) to the electronic key. The electronic key receives the encrypted data  366  and decrypts (step  368 ) the data to retrieve the key code and the lock ID. If the key determines (step  372 ) that the key code  370  returned by the lock matches the key code  332  in the memory of the key, it stores data regarding the access event, including the lock ID, in an audit trail data portion of the key&#39;s memory for audit purposes. 
     The key then proceeds to the third phase of the unlocking process, in which the key communicates to the lock to allow access. To that end, the key encrypts (step  376 ) the received lock ID and transmits the encrypted lock ID and random number to the lock. The lock receives the transmitted data  380  and decrypts (step  382 ) the data to retrieve the lock ID. If the received lock ID  386  matches the lock ID  346  stored in the memory of the lock, the microcomputer of the lock proceeds to unlock the door of the vending machine. 
     The unlocking operation described above has several advantages. It allows the transfer of the lock ID and the key codes between the electronic key and the lock on the vending machine without repeating numbers or a distinguishable pattern of numbers in case of eavesdropping of repeated access attempts. It also prevents a transfer of data between the key and the lock with different encryption codes. Further, it provides a consistent and secure means of data transfer between the key and the lock for a condition where many keys with the same key code will be expected to communicate with many locks on different vending machines containing that key code. This bi-directional challenge-response encryption scheme provides no risk of the keys and the locks going out of sequence, which is a common problem with unidirectional rolling-code encryption systems. 
     The lock ID code is used in the unlocking operation described above for generating audit data for audit trail identification purposes and also for data transfer encryption purposes. In an alternative embodiment, however, it is also be used to provide a method for controlling which vending machines a key is allowed to access. In this method, there may be many keys containing the same key code, and there may be many vending machines that have “learned” the same key code. It is possible, however, to specify which vending machines a given key is allowed to access so that a single key cannot open all the vending machines. Referring to  FIG. 24 , this is accomplished by loading a list of lock ID codes  392  into the memory  330  of that key prior to operation. During an unlocking operation, the key receives a lock ID  374  from the electronic lock on the vending machine and compares the received lock ID with the list of lock IDs  392  in its memory. Only if it is determined (step  398 ) that the received lock ID  374  matches one of the lock IDs in the list will the key proceed to send the unlock command signal (e.g., the transmission  380  in the third phase) to the electronic lock. As shown in  FIG. 24 , the unlocking process is otherwise similar to that shown in  FIG. 23 . This method of access control provides supervisors of the operation the flexibility of allowing or disallowing a given key to access selected vending machines. 
     In an alternative embodiment, an electronic key may also be programmed with other types of limits of operation of the key. For instance, the key may be programmed with limit registers that contain values chosen by a supervisor to limit the operation of that particular key. In a preferred embodiment, the limit registers  400  ( FIG. 20 ) are part of the non-volatile memory  252 . The operation limits include, for example, time of data, date, number of days, number of accesses, number of accesses per day, etc. When the user of the key presses the button on the key to initiate a key code transmission, the microcomputer of the key first compares the limits set in the registers with a real-time clock in the key and an access counter in the key memory. If any of the limits is exceeded, the key will not transmit the key code to the electronic lock and will terminate the operation. 
     Referring to  FIG. 25 , the key operation limits may be set by the supervisor  408  of the employee that uses the electronic key  412  to access vending machines in the field. The limits can be selected by using a personal computer (PC)  410  with the appropriate software program. The limits for each key may be customized depending on, for instance, the work schedule or habits of the employee to whom the key is given. For illustration purposes,  FIG. 25  shows an exemplary user interface screen  416  for prompting the user  408  to enter the limits. After the limits are selected on the PC  410 , they are loaded from the PC into the operation limit registers in the electronic key  412  in a communication process between a key read/write device  418  and the key. During this communication process, other types of data, such as data for updating the real-time clock in the key, may also be loaded into the key. Also, the communication process may be used to transfer data, such as the audit trail data collected from vending machines by the key during previous field operations, from the electronic key  412  to the PC  410 . 
     In accordance with an aspect and alternative embodiment of the invention, an advantage of electronic keys is that they can be used to record and collect and track the attempted accesses of locks on vending machines in the field. Keys that provide this function are of the “auto-tracking” type mentioned above. Referring to  FIG. 26 , with an auto-tracking key  412 , each access attempt triggers an audit data event in both the electronic key and the electronic lock in the vending machine  220 . To that end, a space for audit data is reserved in each of the nonvolatile memories of the key  412  and the lock  248 . During an access attempt, the key  412  transfers the key code  420  and a timestamp  422  to the lock. Regardless of whether the access attempt succeeds or fails, the lock stores the key code and timestamp in its audit data memory. In one implementation, the lock will filter the number of accesses from a given key in a given period (e.g., one attempt per key for every 20 minutes) so that it does not create a separate record for each access attempt. It may, however, include data in the record counting the number of access attempts from the key in the time period. This minimizes the chances that when a key is used to make many access attempts in a row it will fill the audit trail memory and erase existing records of previous access attempts. One way to set this time period in the lock is to transfer the value of the period from a key (which is in turn set by a supervisor using a PC) to the lock. 
     If the access attempt results in a key code mismatch or if the key is disallowed for access because an operation limit in its limit registers is reached, the access process is terminates. In either case, the lock transfers its lock ID  428  to the key  412 . The key is expected to store the lock ID and the timestamp in its audit data memory as an invalid access attempt. 
     If, on the other hand, the access attempt results in a valid match of key code and the key has not exceeded its operation limits, the lock still transfers its lock ID to the key  412 . The key  412  then stores the lock ID and timestamp in the audit data memory as a record of a proper access. In addition, as the electronic key is an auto-tracking key, the lock transfers all the audit data  428  entries in its audit data memory to the key. The data in the audit data memory includes the lock ID, a record for each access attempt that includes the entire key code (including the key ID digits) received from the key that made the access attempt, and the timestamp for that access attempt. The auto-tracking key  412  then stores the audit data  428  of the lock in its own nonvolatile memory. In this regard, each key preferably is capable of uploading the audit data memories of 400-500 vending machines. This eliminates the need for a separate process or equipment in the field for performing the same data retrieving function. 
     When the electronic keys  412  are returned to the home base, the audit data they generated themselves and the audit data they collected from the vending machines  220  can be transferred to a central control computer  410 . The audit data can be downloaded to the PC  410  by the supervisor using the key read/write device  418  that is also used for programming the electronic key. 
     By way of example,  FIG. 27  shows exemplary audit data collected by an auto-tracking key from a vending machine. In this example, the key code stored in the lock on the vending machine is “A100”. The vending machine was accessed using the auto-tracking key on Dec. 8, 2001. Since the key contains the correct key code, the access operation is successful. Thereafter, there were two unauthorized access attempts. The first unauthorized access attempt on Dec. 19, 2001 failed, because the key code (“A500”) in the electronic key did not match the key code in the lock. The second unauthorized attempt on December 20 used a stolen key with the right key code and was successful. When the auto-tracking key is used on Dec. 22, 2001 to unlock the vending machine, the audit data  432  stored in the memory of the electronic lock on that vending machine are transferred to the auto-tracking key, which stores the transferred audit data in its own memory. As stored in the key, the audit data  436  identifies the vending machine from which the audit data are uploaded. The audit data  436  stored in the key are later downloading to the home base PC. 
     Due to the various complexities of this system concerning multiple key users, key codes, and the multiple keys sharing the same key codes, as well as the flexibility provided by the ease of changing access codes of the vending machines in the field, it is often desirable to provide simple diagnostic capabilities to the keys, electronic locks. It may also be desirable to provide special reader tools for use in the field. 
     In one implementation, the electronic key uses its LED light to provides several diagnostic signals to the user when its START button is pressed and when it is communicating with the electronic lock. If the key correctly communicates with the lock and the key codes match, the LED light is on continuously for about five seconds. If the key correctly communicates with the lock but the key codes do not match, the LED light flashes around five times a second for about five seconds. If the key cannot establish correct communication with the lock, the LED light is set to flash faster, such as 25 times a second, for about five seconds. If the key correctly communicates with the lock and the key codes match, but the operation limits set in the limit registers are exceeded, the LED flashes at a lower frequency, such as three times per second for about 3 seconds. If the START switch of the key is pressed and the key does not communicate with the lock and its operation limits are exceeded, the LED first flash quickly, such as 25 times per second, for up to 5 seconds, and then flash three time per second for up to three seconds. 
     In a preferred embodiment, a diagnostic tool  440  is used in the field to communicate with electronic locks on vending machines, which provide diagnostic information in the event of problems with the operation of the lock or the door. As shown in  FIG. 26 , the diagnostic tool  440  includes a display  442  that displays information read from the electronic lock. For instance, the display may show each of the access control key codes stored in the non-volatile memory of the lock, the lock ID of that lock, and any other information pertaining to the state of the electronic lock, such as an indication of whether the lock expects the door to be in a locked or unlocked state based on a position-control feedback measured by the lock circuit. 
     In a preferred embodiment, security measures are implemented in the electronic key concerning key tampering by replacing the battery in the key. It is possible that the employees or thieves that gain access to the electronic keys will attempt to trick the security of the system by tampering with the key. Since the key contains the clock that provides the time and date of access limiting, it is likely the users will attempt to disable or trick the clock to override the access limits. For example, if the key operation limits are set to only allow accesses between 7 AM and 6 PM, the user may attempt to disconnect the battery of the key in-between lock accesses to stop the clock in the key from counting down the time and disabling the key. 
     Referring to  FIG. 29 , to reduce of risk of clock tampering by removing the battery, the key is programmed such that it will reset its clock back to approximately the correct time and date after the battery is reconnected. This feature is provided for both cases of the battery going low naturally or if it is tampered with by the user. To that end, each time the START button  236  of the key is pressed (step  490 ), the microcomputer  280  of the key reads the time and date from the clock  294  (step  492 ), and stores the time and date data  498  in the non-volatile memory  282  of the key (step  496 ). Alternatively, the key may store the time and date periodically, such as every 1-2 minutes. Referring now to  FIG. 30 , if the key battery is disconnected and later a battery is inserted into the key, the key starts a power-up process (step  500 ). The microprocessor is programmed to read the back-up time and date  498  stored in the non-volatile memory  282  (step  502 ) and writes that time and date into the clock  294  (step  506 ). The clock will then run based on the restored time and date as a substitute until the electronic key is re-docked into the cradle and the home base computer  410  stores a new accurate time and date in the clock of the key. When the restored time and date is in use, the key can still be used to access locks on the vending machines as long as the operation limits of the key are not exceeded. 
     In addition to the time-restoration feature, the microcomputer  280  in the key employs logic that counts the number of times the battery is removed and will immediately disable the key indefinitely if the battery is disconnected and re-connected more than a pre-selected number of times, such as three times. Specifically, the microprocessor maintains in the non-volatile memory  282  a counter  512  that counts the number of times the key has been powered up since the last docking of the key. This counter  512  is cleared each time the key is docked. Each time a battery is inserted in the key and the microcomputer  280  goes through the power-up process (step  506 ), the microcomputer  280  reads the counter  502  (step  516 ). If the microcomputer determines (step  518 ) that the counter reading has reached the allowed number of power-up, such as 3 times, it disables the key from any access operation. If the allowed number of power-up is not reached, the microcomputer increments the counter (step  520 ). Thereafter, the key continues with regular key operation, but with each access attempt the key will store a “battery removed” bit with the audit data for that access event in the memories of the lock and the key. This “battery removed” bit indicates that the time and date stamp of the access event is recorded after the key battery was disconnected, and that the accuracy of the time and date is questionable. 
     Referring to  FIG. 31 , in accordance with a feature of an alternative embodiment, the vending machine  220  is equipped with an electronic device for communicating with the home base. The communication device  560  preferably communicates wirelessly, such as over a RF channel, to the computer  410  at the home base of the owner of the vending machine. The vending machine also includes a vendor controller electronic circuit  562  for controlling the operation of the lock  248 . The vendor controller  562  is connected to the lock  248  and the communication device  560 . The electronic lock  248  working together with the vendor controller  562  and the communication electronic device  560  in communication with the home base can accomplish many of the same access control and auditing functions described above and additionally some inventory and money settlement processes. For example, the communication device  560  can receive a command from the home base to disable operation of the lock  560  regardless if an electronic key with the correct key code attempts to access the vending machine. Also for example, the lock  248  can indicate to home base computer  410  through the communication device  560  which keys have attempted to access of the vending machine. This arrangement eliminates the need to use an electronic key to collect, store, and transfer the audit events to the home base via the memory and communication medium of the key. 
     Moreover, the communication device  560  may be used with the vendor control  562  to keep track of the inventory and the cash transactions of the machine. In many cases, when the service person (route driver) visits the machine, his job is to fill the machine and collect money. During this task, the vendor control  562  is involved in interfacing with the service person to ensure the proper resetting and settlement processes take place, and that the service person closes the door of the vending machine. The vendor controller  562  can inform the home base computer of the open/close state of the vending machine door. In the case the Route Driver does not satisfy the conditions of the vendor controller  562  by way of inventory or monetary or debit card processing, the vendor controller can send a disable signal to the electronic lock  248  so the door of the vending machine cannot be closed and locked. Thus, since the service person cannot leave a vendor unlocked, this process would force him to complete the required resetting and settlement processes so the vendor controller can allow the vendor door to be locked before the service person leaves the vending machine. 
     Referring now to  FIG. 32 , in accordance with a feature of a preferred embodiment, the wireless transceiver of the electronic key  226  is designed to have limited transmission range and angle to prevent a vending machine  580  from being accidentally opened due to receiving stray transmission from the key when the key is used to open another vending machine  220  in its vicinity. Specifically, the transmitter  582  of the key  220  has a pre-defined transmission angle  586 . Also, due to the limited transmission power of the transmitter  582 , the transmission from the key  226  has a limited transmission power range  588 , beyond which the signal strength is generally too weak for the transceiver  590  of the electronic lock of the vending machine  220  to reliably detect. In a preferred implementation, the transmission power and the transmission angle  586  of the key  226  is selected such that the width  592  of the transmission pattern at the effective transmission range  588  is about the same or smaller than the width of the vending machine  220 . As mentioned above, in a preferred implementation, the transceivers in the keys and the electronic locks on vending machines are infrared transmitters for transmitting and receiving infrared signals Referring to  FIG. 33 , a functional block diagram is provided of an embodiment of an electronic access control device having two microprocessors communicating with each other wherein the access control device wirelessly communicates with an electronic key. 
     In an embodiment, the electronic access control device  3312  can be completely or at least partially mounted within a vending machine  3314 . The electronic access control device  3312  can include, but is not necessarily limited to, an input device  3394 , a first processor  3390 , a non-volatile memory  3352 , a second processor  3392 , another non-volatile memory  3402 , a driver circuit  3396 , and an electrical device  3398 . 
     The electronic key  3326  communicates with the input device  3394  of the access control device  3312 . The electronic key  3326  preferably includes a non-volatile memory  3382  containing a key code  3388  and an encryption code  3390 . 
     Preferably, the electronic key  3326  uses a wireless means (i.e., radio-frequency, infrared, or the like) to communicate with the input device  3394 . Communication between the electronic key  3326  and the input device  3394  can be unidirectional or bidirectional. It is preferred, however, that the data communicated between the electronic key  3326  and the input device  3394  be encrypted as previously described above. 
     The input device  3394  can comprise a conventional communication interface that uses radio frequency, infrared, or the like for wirelessly communicating with the electronic key. In an embodiment, the input device is a half-duplex IRDA infrared communication interface  254  for communicating with the electronic key. Accordingly, the input device  3394  is mounted on or in the vending machine  3314  so it can receive infrared transmissions. 
     The input device  3394  provides control signals to the first processor  3390 . Although shown in simplified form, the first processor  3390  can include, but is not necessarily limited to, a power supply voltage regulator, a learn switch, an LED for state indication, and a non-volatile memory  3352  for storing key codes  3368 , encryption codes  3370 , and audit data as previously described above. As will be appreciated by those having ordinary skill in the art, the non-volatile memory  3352  can be integral to, or separate from, the first processor  3390 . 
     The first processor  3390  communicates with the second processor  3392  via a communication link  3400  that can be a conventional data communication bus, wiring, or the like. Further, the second processor  3392  can be a conventional microprocessor device or the like. 
     In an embodiment, the second processor  3392  is provided with access to a non-volatile memory  3402  and a driver circuit  3396 . The non-volatile memory  3402  is conventional and thus can be a CMOS RAM, EEPROM, FLASH, or ROM, that is integral to the second processor  3392  or a standalone device or circuit. The non-volatile memory  3402  preferably stores a preset communication code. 
     The driver circuit  3396  can include a conventional lock motor driver, solenoid control circuit or the like for operating electrical device  3398  to effect a desired operation. Accordingly, the electrical device  3398  can be, for example, a solenoid, motor, relay, or the like for opening a lock such as a lock on the door of a vending machine. 
     In an embodiment, but not necessarily, the first processor  3390  can be positioned closed to the input device  3394 , while the second processor  3392  can be located close to the electrical device  3396  and well shielded from external access. 
     In the Learn mode of operation, similar to that previously described above, the electronic key  3326  communicates with the input device  3394  of the access control device  3312 . As indicated previously, proper communication between the electronic key  3326  and the access control device  3312  must be established. This can be done by first placing the access control device  3312  in LEARN mode via a switch ( 262  of  FIG. 19 ). Once the access control device  3312  is put in the LEARN mode, the service person can operate the electronic key  3326  containing preferably at least one desired key code by pressing the button ( 236  of  FIG. 20 ) on the electronic key. This causes the key  3326  to transmit the key code(s)  3388  stored in its memory to the access control device  3312 . If, as preferred, the electronic key  3326  and the access device  3312  employ encryption techniques in their communications, then the electronic key  3326  first encrypts the key code(s)  3388  with the encryption codes  3390  in its non-volatile memory  3382  and then wirelessly transmits the encrypted key code(s). 
     The input device  3394  receives the wirelessly transmitted encrypted code(s) and provides the data to the first processor  3390 . The data is decrypted by the first processor  3390  using the encryption codes  3370  in its associated memory  3352  to obtain the transmitted key code(s)  3388 . In a preferred embodiment, the encryption codes  3390  and  3370  in the electronic key  3326  and the access device  3312 , respectively, are inserted during manufacturing at the factory and different encryption codes can be used for different vending machine owners (e.g., different soft drink bottlers) so the electronic keys given to one owner may not be learned into and used to access the vending machines of another owner. 
     As previously indicated above, if the encryption codes of the electronic key and the access control device  3312  do not match, then the access control device will not be able to successfully decrypt the received key code(s). In that case, the process will end and the lock will not learn the new key code(s). If, however, the decryption is successful, then the access control device  3312  will store the key code(s) at a proper location. In an embodiment, at least one key code  3368  can be stored in the non-volatile memory  3352  associated, or part of, the first microprocessor  3390 . Further, if desired, another key code can be stored in the non-volatile memory of the second microprocessor  3392 . 
     With the key code(s) stored in the access control device  3312 , the device uses the key code(s) for access control. In other words, the access control device  3312  compares the stored key code(s)  3368  with the key code(s) transmitted from the electronic key  3326  to determine whether the vending machine door should be unlocked. 
     In particular, when a wireless signal is received by the input device  3394 , the wireless signal is provided as input data to the first microprocessor  3390  for decryption. The first microprocessor decrypts the input data to obtain at least one transmitted key code that is compared to a key code  3368  stored by a non-volatile memory  3352  associated with the first microprocessor  3390 . If the transmitted key code  3388  matches the stored key code  3368 , then the first processor  3390  sends a special communication code to the second microprocessor  3392  via communication link  3400 . The communication code can, but not necessarily, be encrypted when it is transmitted over the communication link  3400 . The communication code can comprise another (i.e., second) key code that is stored in the non-volatile memory  3352  associated with the first microprocessor  3390 , or the other (i.e., second) key code can be obtained from the data wirelessly transmitted by the electronic key  3326 , or it may have originated from the memory  3402  associated with, or contained within, the second microprocessor  3392 . 
     In the case where the communication code originates in the memory  3402  associated with, or contained within, the second microprocessor  3392 , the communication code can be transferred from the second microprocessor memory to the first microprocessor memory (i.e., the memory that is associated or part of the first microprocessor  3390 ) during an initialization sequence such as during initial power-up. For instance, when power is first applied to the electronic lock, the second microprocessor can transmit the access code and the communication code to the first microprocessor, which then stores the code in memory for subsequent operation. Moreover, encryption and decryption operations between the key  3326  and the lock  3314  can be implemented as described in detail herein. 
     The second microprocessor  3392  compares the communication code with a communication code stored in the non-volatile memory  3402  associated with the microprocessor. If the communication codes match, then the second microprocessor  3392  activates the driver circuit  3396  to energize the electrical device  3398 . 
     As indicated previously, the electronic access control device  3312  can store in a memory a plurality of access attempt records or an audit trail of the lock access attempt history which can be downloaded externally from the lock to an electronic key or another data storage device. Also as indicated previously, the electronic key  3326  can be controlled by operation limit parameters that will control the operation of the key by a clock and limit parameters. Also as indicated previously, the electronic access control device can communicate diagnostic messages and/or codes to an electronic key or a reading and display device. Also as indicated previously, the electronic access control device  3312  can communicate with a home base, the electronic key, or other device for providing access control and auditing functions. In such an embodiment, the vending machine  3314  can include a vendor controller electronic circuit ( 562  of  FIG. 31 ) for controlling the operation of the electronic access control device  3312 . In such an embodiment, the vendor controller can receive a command from the home base ( 410  of  FIG. 31 ) to disable operation of the electronic access control device  3312  regardless if an electronic key with the correct key code(s) attempts to access the vending machine. Also, for example, the electronic access control device  3312  can indicate to the home base computer which electronic keys have attempted to access the vending machine. Moreover, the electronic access control device  3312  can transmit its key codes, as encrypted data, when commanded to do so 
       FIG. 34  shows a system in which one or more programming schemes may be implemented for field-programming the electronic lock  4402  of the vending machine  4400  without having to open the vending machine to access a program switch. Similar to the embodiments described earlier, the vending machine  4400  is equipped with an electronic lock  4402  with a microprocessor-based lock circuit  4406 . The lock circuit  4406  includes a wireless transceiver  4408  for wirelessly communicating with an electronic key  4410  and other devices such as a hand-held programming unit  4412 , as described in greater detail below. The wireless transceiver  4408 , which is mainly used for access control purposes, is connected to the electronic lock circuit  4408  through an access control port  4414 . The wireless transceiver  4408  preferably transmits in a carrier band, such as infrared, that has a short transmission range and a well-controlled transmission pattern. 
     In addition to the access control transceiver  4408 , the vending machine  4400  further includes a second wireless transceiver  4420 , referred hereinafter as the “lock communication transceiver.” The lock communication transceiver  4420  is connected to the electronic lock circuit  4406  through a lock communication port  4422 . In contrast with the access control transceiver  4408 , the communication transceiver  4420  preferably transmits in a carrier band, such as RF, that has a longer transmission range to enables the lock circuit  4406  to communicate wirelessly with an external computing device  4426  without requiring the external computing device to be in close proximity with the vending machine. To communicate wirelessly with the electronic lock, the external computing device  4426 , such as a laptop computer, is equipped with a wireless transceiver  4428 . By wirelessly communicating with the electronic lock  4402  of the vending machine, the external computing device  4426  may perform various tasks, including programming the electronic lock circuit  4406  and downloading audit data as described below in connection with one embodiment. As illustrated in  FIG. 34 , the external computing device  4426  may further include a cradle  4430  for receiving the electronic key  4410  or the hand-held programming unit  4412 . 
       FIG. 35  shows the data stored in the components of the system illustrated in  FIG. 34 . The electronic lock circuit  4406  has a memory that stores the serial number of the lock, one or more access codes, access control parameters, and optionally a digital timebase (i.e., a clock). The electronic key  4410  has stored therein access code(s), control parameters for accessing the lock, and an optional timebase. The hand-held program unit (HHPU)  4412  contains a program command code, access code or codes for accessing locks on vending machines, an optional timebase, and control parameters. The external computing device  4426  has in its memory a timebase, access code or codes for electronic locks on vending machines, and access control parameters for the electronic locks. In addition, the external computing device  4426  may have a database  4436  containing available access codes and control parameters that can be programmed into electronic locks in vending machines. The database  4436  may alternatively or additionally contain programs for computing new access codes and generating control parameters for electronic locks and keys. 
     Turning now to  FIG. 36 , in one embodiment, the programming of the electronic lock  4402  of the vending machine  4400  is accomplished by using the hand-held program unit  4412 . The hand-held program unit is intended to be portable so that it can be conveniently carried by an operator to the physical location of the vending machine. As illustrated in  FIG. 36 , the hand-held program unit  4412  preferably has at least one actuation device such as a push button  4438 . When the transceiver  4440  of the hand-held program unit  4412  is pointed to the access control transceiver  4408  of the lock and the push button  4438  is pressed, a command code  4446  is transmitted to the lock circuit  4406  of the vending machine  4400 . The command code  4446  instructs the lock circuit  4406  to enter a receive mode for receiving a new access code. Next, the new access code is transmitted from the hand-held program unit  4412  to the lock circuit  4406 . The lock circuit  4406  receives the new access code and stores the code in its non-volatile memory. The transmission of the new access code may be done automatically by the hand-held program unit  4412 , or may require the operator to push the button  4438  or another button designated for triggering the transmission. To ensure the security of the transmissions, the transmissions are preferably encrypted. Moreover, the reprogramming operation may involve a bi-directional challenge-response process similar to the one described above with reference to  FIG. 23 . The lock circuit  4406  may also have the capability of using access control parameters, such as the allowed number of access, time and day of the access, etc., in addition to the access code to control the access of the lock. The access control parameters may optionally be first stored in the hand-held program unit  4412  and then transmitted along with the new access code from the program unit to the electronic lock during the programming operation. 
     As part of the code programming process, the electronic lock circuit  4406  may also transmit data such as access codes, its serial number, and/or commands, to the hand-held program unit  4412 . For example, after receiving the programming command code  4446 , the lock circuit  4406  may send its serial number or current access code to the hand-held program unit  4412 , which then selects a new access code for transfer to that lock. In addition, the hand-held program unit  4412  may also take on the function of an electronic key before or after the access code of the lock has been re-programmed. 
       FIG. 37  shows an alternative implementation that is similar to that of  FIG. 36  in that it also uses the hand-held program unit  4412  to program the electronic lock of the vending machine  4400 . The difference is that in the implementation of  FIG. 37  the hand-held program unit  4412  communicates with the lock circuit  4406  through the communication transceiver  4420  that is separate from the access control transceiver  4408  normally used for communicating with an electronic key  4410 . In this regard, the communication transceiver  4420  may transmit data in either an infrared or an RF band. 
       FIG. 38  shows another embodiment that uses the external computing device  4426  to reprogram the electronic lock  4402 . In one implementation, the external computing device  4426  communicates with the electronic lock circuit  4406  through the communication transceiver  4420  that is separate from the access control transceiver  4408 . In this programming scheme, the transceiver  4420  preferably operates in the RF range to provide a longer communication distance so that the external computing device  4426  is not required to be brought very close to the vending machine in order to communicate with the lock circuit  4406 . Alternatively, however, the transceiver  4420  may operate in the infrared band, which may require the external computing device  4426  to be in direct sight of the lock for wireless communication. In another alternative implementation, the external computing device  4426  may communicate with the lock circuit  4406  through the access control transceiver  4408 , although the effective communication distance will be smaller, requiring the external computing device  4426  to be placed closed to the vending machine. 
     In this embodiment, the lock circuit  4406  preferably has the capability of using access control parameters to control the access of the lock. For example, the access control parameters described above, such as the allowed number of access, time and day of the access, access code, etc., may be stored and used by the lock circuit. To program the lock circuit  4406  with a new access code and/or new control parameters, the external computing device  4426  first polls the electronic lock circuit  4406  of the vending machine by sending a Request Data command. The Request Data command also servers as a program command telling the microprocessor of the lock circuit  4406  to enter a program mode. During the polling process, the external computing device  4426  issues commands to request the lock circuit  4406  to transmit data such as the serial number of the lock, access codes, and/or the audit data of the lock. The lock circuit  4406  responds by transmitting at least the data requested by the external computing device  4426 . After receiving the requested data from the lock, the external computing device  4426  may generate a new access code for the lock and/or other information pertaining to accessing the lock, such as encryption codes, time parameters, access control limits, etc. To that end, the external computing device may have a database  4436  that contains appropriate access codes and control parameters that have been calculated previously for electronic locks, electronic keys, or both. Alternatively or additionally, the external computing device  4426  may also have programs that implements mathematical algorithms for computing the access codes and control parameters. Such calculations may generate the access codes randomly or based on a function that includes the time as a variable. The external computing device  4426  then wirelessly transmits the new access code and/or control parameters to the electronic lock circuit  4406  via the wireless communication link between the transceiver  4428  and the communication transceiver  4420 . To protect the transmissions from eavesdropping, the transmissions are preferably encrypted. Also, the reprogramming operation may involve a bi-directional challenge-response process similar to the one described above with reference to  FIG. 23 . 
     After receiving the new access control data from the external computing device  4426 , the electronic lock circuit  4406  recalibrates the lock control functions based on the received data. For example, after receiving the access code or codes and parameters, the lock circuit  4406  may change the access codes and access limits based on the received access control parameters. In this way, the electronic lock is reprogrammed by the external computing device  4426 . Next, the external computing device  4426  may optionally be used to program an electronic key  4410  that can be used to visit and access the vending machine  4400  through the access control transceiver  4408 . To that end, the electronic key  4410  is connected to the cradle  4430 , and the access code that has been programmed into the lock is transmitted via the cradle into the key, together with any other appropriate access control parameters for the key. The key  4410  can then be used to access the vending machine by communicating with the electronic lock circuit  4406  via the access control transceiver  4406  based on the newly programmed access code(s) and control parameters. 
     By way of example, in the context of servicing vending machines, an operator may drive to the building in which the vending machine is located. In his service vehicle, the operator uses a laptop computer that functions as the external computer device to wirelessly communicate with the electronic lock of the vending machine by sending RF signals. By means of the RF communications, the laptop programs the lock of the vending machine with a new access code and control parameters. For instance, the new access code may be given an active period of 15 minutes, and the operator has to access the vending machine within that time period. The operator also uses the laptop to program the same new access code into an electronic key. The operator then walks up to the vending machine and uses that electronic key to communicate with the lock circuit via the access control infrared transceiver to open the door of the vending machine. In this scenario, the lock of the vending machine and the associated key are programmed “on the spot.” After the operator has accessed the vending machine, the access code programmed into the electronic lock may simply go expired. In other words, the lock of the vending machine may not have any valid access code until it is reprogrammed next time by the external computing device. 
     In an alternative implementation, the same process of programming the lock with an external computing device and then accessing the lock with an electronic key is utilized. In this programming scheme, however, the access information transferred to the electronic lock circuit  4406  is based on access code(s), access limit parameters, etc. that are already in the electronic key  4410 . In other words, the external computing device  4426  does not generate the access control information, but instead takes the information from the electronic key. The electronic key, for example, may contain the access codes and access limits for the lock for that day. To reprogram the electronic lock, the electronic key  4410  is placed in the cradle  4430 , and the external computing device  4426  reads the access control information from the key and transmits the information to the electronic lock circuit  4406  via the communication transceiver  4420 . After the electronic lock is programmed with the new access code and other control parameters, the operator takes the key  4410  to the location of the vending machine and uses the key to access the lock by communicating with the lock via the access control transceiver  4408  based on the new access code and/or operation parameters programmed into the lock. 
     Before or after the electronic key  4410  is used to access the electronic lock, the lock circuit  4406  may also send audit data for both successful and unsuccessful access attempts to the external computing device  4426  via the communication transceiver  4420 . Alternatively, the audit trail data may be downloaded from the lock circuit  4406  into the electronic key  4410  when the key is used to access the electronic lock. 
     To set the access control parameters for electronic keys and to manage the audit data collected by the electronic keys from the vending machines, an electronic key management system (or station)  5030  is provided in an embodiment shown in  FIG. 39 . The key management system  5030  includes a computer  5032  which may be a desktop personal computer (PC), with appropriate computer software and hardware for carrying out the functionality of key management and database operations. The software program  5034  for key management and database operations may be a Visual Basic program executing on the PC. The computer  5032  also includes a database for storing data for key management and audit data collected from vending machines. As used herein, “database” may include data files as well as a database program. In one implementation, the database  5035  may be a Microsoft ACCESS database residing on the PC  5032 . 
     As illustrated in  FIG. 39 , the electronic key  5031  includes a status indicating device which may be an LED light  5038 , and a push button  5039  that when pressed causes the key to start wireless transmission. To communicate with the electronic key, the key management system  5030  includes an interface device for forwarding and receiving communications to and from an electronic key. In the embodiment illustrated in  FIG. 39 , the interface device is in the form of a cradle  5036  (or docking station) that interfaces the key to a communication port  5033  on the PC  5032 . The cradle  5036  has a receiving place for receiving the electronic key, and indicators such as a ready/wait light  5040 . 
     In accordance with a feature of the embodiment, the database  5035 , software  5034  and cradle  5036  transceiver interface systems are limited for secure operation on only one particular computer  5032  by means of registration. The software programs and the cradle can properly function only after they are registered with an authorized control center. Thus, a thief cannot install stolen components on a computer at an unauthorized location. The steps of an exemplary registration process are described with reference to  FIGS. 40A and 40B .  FIG. 40A  shows an interface screen that presents a registration form  5042  and a Software Registration Menu. After the software programs are installed on the computer  5032 , a user may click on a “registration” tab in the menu bar to bring up this registration form. To fill in the required data, the user looks at the bottom of the cradle  5036  for the cradle serial number, and enters this number into the form  5042 . The user looks at the compact disc (CD) containing the key management software for the CD serial number, and enters it into the form. The user also fills in other required information, such as contact information including the bottler name, contract name, address, phone number, etc., into the registration form. Once the registration form  5042  is properly filled, the user clicks on the “Generate System ID#” button  5044 . After this button is pushed, the software program generates a system ID number for this system based on the serial numbers and/or other information entered by the user. The system ID number appears at the bottom of the form  5042  under the “Get Registration #) button  5045 . The user then clicks on the “Get Registration #” button. In response, the software program generates a registration form containing the user-entered information and the system ID number, and sends the form to the printer for printing, as illustrated in  FIG. 40B . This registration form  5050  is then sent, for example via facsimile, to the control center (e.g., TriTeq Corporation) so that the control center can register the key management system using the system ID number. The control center then issues a special code  5053  as a registration number for the user&#39;s system. The special code is generated based on the system ID number and possibly other information provided by the registration form  5050 . This registration number  5053  may be sent to the user in a registration response form  5052  that may be transmitted via facsimile to the user. The registration number may also be sent via other means of communication, such as email, mail, or voice communication (e.g., a phone call). The user then goes to the next screen  5055  of the user interface for software registration, and enters the received code  5053  into a provided field. After the user clicks an Enter button  5054 , the software stores the entered registration number in a special memory location. 
     The registration process described above links together the serial numbers assigned to and/or embedded in the software  5034 , the interface cradle station  5036 , and the computer  5032  to create an authorization number stored in the database  5035 . Each time the software  5034  is restarted, it reads the serial numbers of each of the components to calculate the authorization number, and then compares this number to the authorization number in the database to make sure they match before operating. If the calculated authorization number does not match the stored authorization number, the software does not allow the user to access the system management functions, and the system is inoperative. 
       FIGS. 41A &amp; 41B  describe how the database interaction with the docking station or cradle is initiated by starting the software system which allows database accesses and data transfer to/from the database. One password is optionally required to initiate the “User” operation mode. As shown in  FIG. 41A , after the software is started, the software presents a window  5058  on the computer screen for the entering of a password. The software then presents a key control window  5060  that contains various control parameters or limits for controlling the operations of the electronic key. For instance, the key control screen in  FIG. 41A  includes fields for the name of the user of the key, the ID number for the electronic key, the key type, the total number of accesses allowed, the allowed number of accesses per day, the start and end times of the operative period of the day, the expiration day and time, and the number of days in which the key is valid, etc. 
     Referring to  FIG. 41B , when the software program  5034  is started, the software presents the password window as shown in  FIG. 41A  and waits to receive a user mode password. When a password is received, the program determines whether the password is correct (step  5060 ). If the user password is incorrect, the software program exits from operation. If the user password is correct, the program determines whether the system is properly registered in the way described above. If the system is registered, the program works on the database  5034  by eliminating old events and compacting the database (step  5062 ). The program then turns on the cradle  5036 , and waits for transmissions from an electronic key docked in the cradle. 
     Turning now to  FIG. 41C , to initiate a docking or refresh operation of the key  5031 , the key is placed within communication distance of the cradle  5036 . As shown in  FIG. 39 , the cradle  5036  may have a receiving location on its top into which the key may be placed. The user then presses the transmit button  5039  of the key  5031  to cause the key to start transmission. The transmission from the key is received by the cradle  5036  and forwarded to the computer  5032 . Likewise, communications from the computer  5032  are sent to the cradle  5036 , which then transmits the communications to the key  5031 .  FIG. 41C  illustrates that first the key  5031  and cradle  5036  exchange encryption messages to ensure that an authorized key is communicating with the station. To that end, the cradle  5036  includes a microprocessor for providing the processing power and has software programs including an encryption program for handling the encryption/decryption involved in the challenge-response communications and any subsequent communications. Next, if the key contains access audit data collected from vending machines in the field, the data is downloaded from the key and stored in a buffer  5064 . The data in the buffer  5064  may then be sorted and loaded into the database  5035 . The new operation limits (see  FIG. 41A ) pre-set by a supervisor for that electronic key are then downloaded into the key  5031 . 
     In accordance with a feature of the embodiment, the operation of refreshing the key and downloading data from the key is automatic, without requiring a user to oversee or activate each of the steps involved in the process. All the user has to do to initiate the key refreshing operation is to place the key  5031  in the cradle  5036  and press the transmit button  5039  of the key, and the software program  5034  will finish the operation without requiring further attention from the user or system administrator. During this process the database  5035  proceeds to service the key without prompting the user to enter any information or data at the computer either before or after the key is initiated. As a result, the key refreshing operation may run in the background, without the need to have an open window on the computer screen, thereby allowing the computer  5032  to be used for other operations such as word processing or communications over the Internet. To service the next key, the previous key is removed, the new key is inserted and its transmit button is pressed. Again, the database proceeds to service the key without prompting the user to enter any information or data at the computer either before or after the key is initiated. The docking or refresh operation can be performed without the supervisors present, which allows the system to perform without daily maintenance. 
       FIGS. 42A &amp; 42B  illustrates an advanced set-up feature of an embodiment of the key management system that is only accessible by entering a secure operating mode, which may be either the “Supervisor” or “Administrator” modes. As shown in  FIG. 42A , the software first presents a key control window  5070  similar to that in  FIG. 41A . By clicking on the Mode option in the Menu bar, a user can select to run the software in a Supervisor mode or a User mode. Selecting the Supervisor mode causes the software to open a password entry window for either the administrator or supervisor. The user then enters the password as an administrator or supervisor into the field provided. In one implementation, an administrator oversees multiple supervisors, while each supervisor supervises multiple users to which electronic keys are assigned. When a user signs in as the administrator, he can use the software to add or remove supervisors from the key management system as well as administrating the functions of the key management system. A supervisor can use the software to add or remove electronic keys and/or key users, and set or change key limit parameters. 
     As shown in  FIG. 42B , when audit data is downloaded from an electronic key, the software program determines whether it is in the administrator mode or supervisor mode (step  5080 ). If neither, the program finishes the key refreshing operation by loading new key parameters into the key. If the program is in the administrator or supervisor mode, the program checks the audit data received from the key to see whether the data contains identifications of any vending machine electronic lock that is not found in the database (step  5081 ). In this regard, the audit data stored in an electronic key are collected from electronic locks in vending machines accessed using the electronic key. The audit data collected from an electronic lock contains, among other things, a serial number of the electronic lock. It is possible for the electronic lock of a vending machine to be programmed in the field to work with a given key before the ID number of the lock is registered in the database of the key management system. If the key management program finds a new lock serial number in the audit data downloaded from an electronic key, it prompts the user to enter the lock information into the database (step  5082 ). If the user selects not to do so at that time, the program continues the key refreshing operation. If the user selects to enter the lock information, the program present a user interface window (step  5083 ) to allow the user to enter information about the electronic lock (step  5084 ). The program then continues to finish the key refreshing operation. 
     In accordance with an aspect of the embodiment, the electronic keys contain certain key codes for access authorization purposes. It is desirable to limit which keys can be serviced by which computers such that stolen or lost keys cannot be serviced at computers they are not authorized to be serviced at. Thus, the database preferably contains a feature to limit which serial number sequence keys it will service and which it will not service. If a key is not in this serial number range, the database, computer, and software will refuse to service it. The limit parameters are usually entered into the database by a supervisor just after installing the software. 
     Key Set-Up 
     Certain set-up procedures are implemented in the system in order to make the security features of the system useful and easy to use.  FIGS. 43A &amp; 43B  illustrate these features. First, the electronic keys need to be assigned to the employees. This is accomplished by a simple operation, as shown in  FIGS. 43A and 43B . First, a new key never previously initialized (or not contained in the database) is placed within communication distance of the cradle station interface and the transmit button of the key is pressed. Next, the supervisor is prompted to enter the name or identifier of the user to which the key is to be assigned (step  5086 ). The supervisor enters the required data, and the data is stored in the database (step  5088 ). If it is for a new key user, the process is described in  FIG. 43B . The software recognizes automatically that a new key is introduced into the system. In one implementation, the key indicator light stays “ON” and the cradle light stays “RED” when it is communicating with the key. Afterward, the program provides the user interface screen  5090  shown in  FIG. 43B  to prompt the supervisor or administrator to assign the key to either a new user or an existing user. If the supervisor presses the “Assign New User” button  5093 , the screen  5096  appears for the supervisor to enter information regarding the new user who is going to use the key. After entering the information, the supervisor clicks on the “Accept” button, and the new user information is stored in the database  5035 . Next, the transmit button  5039  of the key is pressed again, and the program presents the key control window to allow the supervisor to set the limits for the key operation. When the user enters this name, the database links the serial number embedded in the non-volatile memory of key with the name for reference purposes. Also, a set of default limits are assigned to the key in the database, such as 200 total accesses, 20 access per day, 6 AM to 6 PM operation, 7 days of operation, Monday through Friday operation.  FIG. 43A  also illustrates how only the supervisory or administrator sets the database up to allow the territory code to communicate to the database. 
     In managing the keys in an on-going basis, the supervisor may use the system to check the limit parameter status of the keys to quickly see which keys are either expired or approaching the end of their operation limit parameters. This is accomplished for example by selecting the “Edit Key Limit” menu on the main screen of  FIG. 42A . In response, the program displays a list of the registered electronic keys and for each key the expected time and date the key will exceed its limits in a row and column format for viewing by the user. 
     Next, the electronic locks to be accessed with the keys need to be assigned to Customers, locations, and/or asset identifier numbers (identification data).  FIGS. 44A-44C  illustrate two methods. This procedure is necessary because the lock is initially identified by the database using a lock serial number embedded inside the lock non-volatile memory that is not easy or obvious for the user of the system to reference or identify to. Once each lock is referenced to a number or name that the user can more easily identify with, understanding and using the audit trail data will be more likely. There are several possible procedures for entering the lock information. Each procedure is possible even if the lock is remotely located from the computer and either cannot or does not directly transfer its serial number to the computer and database. 
     In one procedure shown in  FIG. 44A , the lock serial number  6090  is printed on a label  6091  attached to the lock as an alphanumeric number or as a barcode or other identifier. This number can be visually read and recorded in a form  6093  along with the customer, location, and/or asset identifier number for the lock, and then manually entered into the database  6035 . The disadvantage of this system is if the serial number label is lost or not legible, it would be difficult to identify the electronic lock. 
     In another procedure also shown in  FIG. 44A , the lock serial number  6090  is not printed on a label, but is read from the lock by a diagnostic tool  6092  to make certain the correct serial number is recorded. This number can be visually read from the tool display, recorded along with the customer, location, and/or asset identifier number, and manually entered into the database. In this procedure, a lost label on the lock will not impede the process. 
       FIG. 44B  describes the manual entry process of entering the collected lock, vending machine, and location information and entering it into the database. In the shown example, a key assigned to a user “Gary Myers” has visited a new vending machine that are not registered in the database  6035 . The electronic lock information is time-stamped into the key when the key is used to access the lock. When the key user returns to the key management system  6030  and places the electronic key into the cradle  6036  for key refreshing operation, the lock information is downloaded from the key to the computer. The program notices that the downloaded key data contains new lock information not already entered into the database. For each new electronic lock identified in the key data, the program presents a “New Lock Detected” window  6100  on the computer screen showing the lock serial number and the time at which the lock was accessed. When the user clicks the “Enter Lock Information” button, the program presents a “New Lock Data” screen window  6102  to allow the user to enter detailed information about the vending machine containing that electronic lock, such as the vending machine asset number, customer number, route number, date in service, and location address, etc. After entering the information, the user clicks the “Update Lock Information” button, and the information is stored into the database. The program than presents another “New Lock Data” screen for the next new lock identified in the downloaded key data. 
     In another procedure shown in  FIG. 44C , the user has an electronic tool  6094  that electronically reads or scans the serial number  6090  from the electronic lock (either by communicating with the lock or reading the printed label) and electronically reads or scans an identifier label  6095  on the vending machine  6096 . This electronic reader or scanning device links the two identifier numbers together in memory. This procedure can be repeated for many vending machines for as long as the reader does not run out of memory. After the scan/read process is completed, the reader  6094  can download its data into a computer that can ultimately transfer this data to the database. In this procedure, the lock and vending machine data is electronically linked, so the manual data entry procedure can be avoided. 
     Lock-Database Data Exchange 
     In accordance with an aspect of the embodiment, data may be exchanged to/from electronic locks of vending machines and the key management database  5035 . One method involves using an electronic key to collect the audit information in the lock and ultimately transfer this data to the database  5035 . In alternative embodiments, wireless communications may be used for the data transfer. For example, the lock can communicate directly (or indirectly) through a wireless medium to a computer transceiver interface to transfer the data to/from the database. The preferred embodiment described below uses the electronic keys to transfer the access limits and the audit trail information, but this embodiment is not limited to this method. 
     During service of the key  5031 , data is exchanged from the key to the computer  5032  and from the computer to the key as described in  FIG. 49 . Before this exchange takes place, the cradle  5036  is in the receive mode, wherein any transmission signal from the key will initiate the data exchange process. The timing and sequence of the data exchange is automatic, and it is only necessary to initiate one start operation at the key to exchange the data in both directions. The communication between the key and the cradle is preferably protected by bi-directional encryption methods. During the process, the program determines whether the key is transmitting to the cradle (step  6110 ). If the key transmission is received, the program determines whether the key is an existing key or new key (step  6111 ). If the key is an existing key, the data stored in the key is downloaded from the key (step  6112 ). The program then checks whether the key parameters are healthy (step  6113 ). If so, the program retrieves or recalculate new limit parameters for the key, reset the clock in the key, and upload the limit parameters into the key (step  6114 ). The computer will proceed to service the key provided it is authorized to do so. Such authorization may be provided in the database locally stored on the computer hard drive. One can have such authorization at multiple computers if the authority is granted. 
     In the event of multiple computers authorized to service the same keys, rather than having multiple computers with multiple databases local to the respective computers, it may be more convenient to have one database residing on a central server or shared drive so more than one computer and cradle can be used to service the keys. Thus, the authority to service the key resides in one database and all of the data exchanged is managed in one database rather than multiple databases. In that case, the data exchanged from the key to the computer may be immediately transported to the database or stored locally at the computer and later processed by the computer and loaded in the remotely located database. This may be a more desirable process since the data transfer may be very time consuming during heavy traffic hours on the network and may better and more reliably be transferred during low traffic times. 
     During this data exchange process, the health of the electronic key can be diagnosed. For example, the clock in the electronic key is read by the computer and compared to the clock in the computer. If there is a mismatch in time, the computer can alert the supervisor that the key can a faulty clock or battery. Likewise with the memory in the key. If the data exchange process is not successful, the battery or the memory may be suspect to be faulty, and the computer will display this fault for the user or the supervisor so the battery can be replaced or the key taken out of service. 
     Audit Data 
     During service of the key, the vending machine audit data collected by the key is downloaded from the key to the cradle  5036 , next to the computer memory buffer  5064 , and last to the database  5035  of the computer. The data is managed by the supervisor by allowing each lock serial number to be identified in the database by the customer, location, and/or asset identifier number as previously described is set-up. The software may allow several options for managing this data in the database. This process is executed only one time for identifying the asset number, and one time for each time the vending machine is assigned to a customer or a location. The processes for identifying this data are as follows: 
     Pop-Up Request Process 
       FIG. 44B  illustrates this process. In this process, the software will run a test while in the supervisor mode that will search the lock serial number in the data base. If no such number is identified, the software will prompt the supervisor to enter the data. The software will provide as much information about the vending machine as possible to help for the identification, such as the time and data the lock was first put into service or accessed. 
     Manual Process 
     The software will provide a menu to select the identification process. Next, a drop down list will list in numerical order all lock serial numbers that are not identified. Next, the user will select the lock that he/she wishes to identify. After selected, a screen is provided to enter the data. Also provided is a field for entering the effective data in case the identification data is entered several days or weeks after the data the data is valid. 
     This process can also be executed when viewing audit events from the database. In this situation, the lock serial number is displayed to identify the vending machine (in lieu of the vending machine asset number, customer, and location data). By selecting this number from this display position and clicking, the screen to enter the vending machine data will pop-up for ease of data entry. 
       FIG. 44B  also illustrates that this process is also used after a lock is identified but the user wishes to change or modify some of the data, such as changing the customer information or location if a vending machine is moved or relocated. In this situation, the effective date field is used to properly record the exact date the change took place in case the data entry follows the change by a delay period. 
     Automatic process. It is possible for the identification data to be transferred automatically into the lock database. This identification data will be entered separately from another computer and/or database which separately contains the vending machine identification data. 
     Referring now to  FIG. 45 , as audit data is received from the key it is compared to previous data in the database. Since one or more key may bring duplicate access audit data back to the same database, it is necessary to compare the new data received from the keys with the data presently in the database and discard the like data so duplicate access data is not stored. To that end, when the program receives data downloaded from the key regarding an access attempt event (step  6120 ), it searches the database for any event that is duplicate to the downloaded event (step  6121 ). If a duplicate event is found in the database (step  6122 ), the downloaded event is discarded. Otherwise, the event is stored into the database (step  6123 ), and the program moves to the next event described in the downloaded data. 
     If access data is determined to be new, it is stored in the database  5035 . Suitable data sorting techniques are preferably used in order to efficiently store this data, and to efficiently retrieve this data in the future, and in the future compare this data to new data collected. The software shall be configured such that the audit information in the database cannot be modified or deleted, either accidentally or on purpose, in order to preserve the integrity of the security monitoring system. After audit data is stored in the database, certain data sorting techniques are required to make the viewing of the data useful. 
     For example,  FIG. 46  illustrates it is possible to sort and view the data by Access, by Driver or Employee, by Asset number, or between certain time and date periods. Each of these sort parameters can be combined to sort multiple combinations of parameters. Also, as the audit information is displayed, unusual activity that occurred before or during the access event can be displayed, such as Battery Removed (from the key), Bad Route, Limited, and Unauthorized. To view the audit trails data, the user either clicks the “Audio Trails” button at the bottom of the Key Control Data screen  6126  or use the task bar menu. This function is only available to supervisors and administrators. The program then displays the audit trails screen  6128 . The bottom portion of the screen  6128  presents sorting options that allow the data to be sorted in various ways, such as by time, access, key user, or asset number, etc. Different combinations of these options may be used to refine a search. 
     The audit trails data may also be printed. In one implementation, the printing options available are “Automatic Audit Printing” and “Print Current Screen.” Automatic printing allows for printing when a key refresh is executed and prints all the new events the key has encountered. The audit screen does not have to be displayed on the computer screen to enable printing. 
     Limiting Operational Parameters for Keys 
     Limiting operational parameters are available for keys. To ensure the security of the system, in a preferred embodiment such new limits can be assigned only when the computer is in the Supervisor or Administrator modes.  FIGS. 47A-47C  and  FIG. 48  illustrate the process. 
     In  FIG. 47A , if the supervisor wishes to assign a custom (non-default) set of parameters to this key, he selects the “Edit Key Limits” option in the menu bar of the screen  6130  and then selects the “Set User/Key Limit” option from the drop-down menu (step  6138  of  FIG. 47C ). In response, the system program presents a drop-down list  6132  of keys (by names assigned to the keys) which also displays the expiration dates of the keys (step  6140  of  FIG. 47C ). Next, as shown in  FIG. 47B , the parameter customization screen  6136  is displayed by selecting the user or key. This screen shows the key parameters since the last key refresh operation. For security reasons, the software tracks which supervisor last authorized limit changes. By clicking on the two buttons “View Present Limits” and “View Previous Limits,” the user can see when the last changes were made on the key and by which supervisor (step  6142  of  FIG. 47C ). On this screen, the pointer will move the curser to the parameter the user wishes to change. The user then enters the desired value (step  6144  of  FIG. 47C ). After typing in the change, another parameter may be selected and changed. When all parameters have been changed, the “Accept” button is selected to record the new parameters in the database (step  6146  of  FIG. 47C ). At the time these are stored, the name of the supervisor operating the computer is also stored to archive the authorization in case a key is given limits beyond their approved level and an audit of who assigned these unauthorized limits is required. 
     A “Disable FOB” button  6137  is provided in the screen  6136  to disable the key at its next refresh. In this regard, if the key reaches any of the limits, it will become disabled. The key will indicate that it is disabled by flashing brightly three times when the key is in the cradle and the transmit button of the key is pressed. 
     After the new parameters have been stored, prior parameters for this key are also kept in the database for easy viewing. In addition, the time and date of the prior docking event and the parameters can be stored and easily viewed. 
     Later, in a key refreshing operation, the button of the key is pressed on the key and the limit parameters are loaded into the memory of the key.  FIG. 48  illustrates by way of example the process of re-calculating the limit parameters during the key refreshing operation. The program  5034  takes the limits defined for the key from the database (step  6150 ) and, at the time of refresh, using the existing date and time to calculate certain date specific limit parameters such as the date the key should expire and the days the key should operate (step  6151 ). Last, these parameters are loaded into the key (step  6152 ). This process allows the supervisor to maintain work schedules in the database for each employee and as long as the schedule does not change the expiration limits will be properly re-calculated at the time of each refresh. Thus, the supervisor does not need to maintain key parameters on a routine basis, as they are automatically calculated at each refresh based on the database information for each key. 
     In accordance with an aspect of the embodiment, it is advantageous to provide the capability of more than one docking station or cradle to service the same keys and vending machine locks. This is accomplished by providing a mechanism for either (1) multiple cradles communicating with multiple databases, wherein these databases would be synchronized and merged from time to time ( FIG. 50 ); or (2) multiple cradles communicating with a single central database ( FIGS. 51-53 ). The advantages and disadvantages of each configuration are described below. 
     Multiple Cradles Communicating with Multiple Databases 
     In one configuration illustrated in  FIG. 50 , multiple cradles are located at multiple separate locations, with each cradle interfaced to a PC containing separate databases. For simplicity of illustration,  FIG. 50  shows only two cradles  6160  and  6161  attached to computers  6162  and  6163 , respectively, but more cradles and computers at other locations may be included. In the illustrated embodiment, the database  6164  is accessible to the computer  6162 , and the database  6165  is accessible to the computer  6163 . The databases  6164 ,  6165  may be local to the computers  6162 ,  6163 , respectively, or may be at remote locations and connected to the computers via network connections. It is possible to allow electronic keys to visit and be refreshed by more than one cradle/database. One way to accomplish this is to initialize each key into one cradle  6160  or PC database  6164 . Once each key  6031  is initialized, the databases  6164  and  6165  may be synchronized. Synchronization is accomplished by exchanging the key and vending machine lock data from one database  6164  to another  6165  and vice versa until all databases share the same key and vending machine lock data. This may be accomplished, for example, by creating an “export” file by the export utility from each database that contains the key and vending machine data of the database. 
     The user interface screens  6167  and  6168  for this operation are shown in  FIG. 54 . In the screen  6167 , the user selects to export the database, and in the screen the user identifies the path to the database file. In the illustrate example, the export directory contains the file DBOut.mdb as the container of the export file. The export file may be stored on a transportable medium, such as a floppy disk, a CD ROM  6157 , a USB key, a memory card, etc. Alternatively, the export file may be transmitted to another computer via a network  6158 , preferably in an encrypted format to ensure the security of the transmission. This export file  6166  is next presented to another computer database by using the import utility. This import utility will search for data in the export file that is not in the local database, and load this new data into the local database. If the data presented by the export file is a duplicate of data already existing in the database running the import utility, the data is not imported as a duplicate and is discarded. For example, if a vending machine lock serial number and location is in the export file  6166  and presented to the database  6164  by the import utility, but already exists in the database, it is not entered into the database. This import and export procedure should be executed on a regular basis and the key and vending machine data will stay consistent in each database. 
     Multiple cradles communicating with a single database: In an embodiment of this configuration shown in  FIG. 51 , multiple cradles  6171 ,  6172 ,  6173  are located at multiple remote locations, each interfaced to a separate PC  6174 ,  6175 , or  6176  that has access to a shared database  6180  via a network connection such as a local-area network (LAN)  6179 . Since there is only one database, there is no need for synchronization. In this embodiment, each cradle and PC has access to send/receive data to/from the network-centralized database  6180 . There are several issues about giving access to the central database  6180  to more than one computer. One such issue is if two computers attempt to access the database at the same time, data could be lost or over-written. Another concern is the time it takes to access and communicate with the database. For example, if a significant amount of data must be downloaded from a key at one station, this download process could take several minutes to finish. If another key is also trying to download data and receive new access limits from another computer and cradle, the waiting time could be significant. 
     Thus, it is a feature of the embodiment to provide multiple cradles with access to the same database and provide a fast refresh time so employees are not delayed waiting for their keys to be refreshed. One mechanism to accomplish this is for each computer  6174 ,  6175 ,  6176  to hold a refresh buffer  6181 ,  6182 , or  6183  locally in its PC in order to allow for fast refreshes during busy working hours, and during non-work hours when network traffic is minimized the PC will upload it&#39;s data in the database  6180  on the network. Also in this example the local PC may use the refresh buffer as a local database, or use a separate database, for holding the key limit data. This allows fast refresh of key limits, and would store the audit trail data in the buffer. A copy of the shared database is downloaded from the shared drive by each station and stored locally. In the case the connection to the shared database  6180  is interrupted, each individual station can continue servicing keys without interruption using the local database. In this mode, typically no changes or additions are allowed to the database such as key limits and vending machine information. 
     Database Compacting and Archive 
     Compacting and Archiving of the database are tasks that need to be executed at a frequency dependent on the amount of data that is being added to the database. The more data that is added, the more frequent these task should be executed. In one embodiment, the system allows the user to select an automatic compacting and archiving of the audit trail data. Also allowed is selecting automatic exiting of the software and automatic login of the software at selected intervals.  FIG. 55  shows a user interface screen  6190  for a user to select the parameters. In this example, the user selects the system will automatically compact and archive each 45 days. Also selected is the path &amp; location of the archive  6192 . In addition, the system is capable of monitoring the amount of data entering the database and executing an automatic compaction and archive if a certain volume of data is moved into the database. 
     System Start/Exit 
     The system is capable of automatically starting up and exiting from operation on a daily basis. The start and stop times can be pre-determined and entered into the system as a scheduled task.  FIGS. 56-58  show a sequence of user interface screens  6193 ,  6194 ,  6195 ,  6196 ,  6197 ,  6198  to illustrate an example of how the system is scheduled to start-up at 4:00 AM every day.  FIGS. 59-60  contains user interface screens  6200 ,  6201  that illustrate an example of how the user selects the system to automatically exit from operation at 1:30 AM each day. 
     In an alternative embodiment illustrated in  FIG. 52A  referred to as the pre-enterprise configuration, the single database configuration uses a dedicated database server  6208 . This configuration contains all of the above-described features from the LAN network single database embodiment, while each station is allowed to access a dedicated database server  6208  (SQL, Oracle, etc). A local station  6210  connecting to the database  6209  will be accomplished using the standard “Data Source (ODBC)” included in all Windows operating systems. After connection to database is accomplished, the user uses the key control operation features the same as in the previous configuration. Potential advantages of this configuration are increase database reliability, faster response time on accessing, changing, or adding records to the database, and significantly less data traffic. 
     Referring to  FIG. 52B , the added capacity of a dedicated database server  6208  can be used by mounting multiple databases  6211 ,  6212 ,  6213  for serving multiple locations  6221 ,  6222 ,  6223 , respectively. In such instances the databases  6211 ,  6212 ,  6213  can be identified by the specific city code, or group of city codes each database represents. A location can be, for instance, a cluster of bottling stations and/or a bottling station and several satellite locations. Stations from each location are assigned rights to access only the database they are associated with. For instance, computers at the location  6221  may access only the database  6211 , and computers at the location  6222  may access only the database  6212 . This configuration adds the benefit of creating global access reports that will include reports from all locations. Another benefit of this configuration is the option of remote control and administration of database from a remote location. For example, if appropriate rights are assigned to Station  6225  at Location  6221 , this station can manage keys, users and vending machines at location  6221  as well as the other locations. By using a LAN type network, the security of this configuration should adequately prevent hackers from gaining access to the database and the security of the system. 
     In another alternative embodiment of the single database configuration illustrated in  FIG. 53 , a web server  6230  connected to a database server  6231  is used. This configuration is referred to as the Enterprise configuration. Each of the individual stations uses a simple web browser (e.g., Internet Explorer, Netscape, Opera, etc.) to communicate with the web server  6230  to access the database or databases  6240  maintained by the database server  6231 . In this way, the individual stations can accomplish functions related to key refresh, adding keys and users, adding vending machines and asset numbers, and modify key settings as in the previously described configurations. In the event of lost Internet connection, the stations in this configuration operate a simplified version of the software as described in  FIGS. 51 &amp; 52  for refreshing keys while the connection with the web server  6230  is severed. One benefit of this configuration is the ability to use the Internet infrastructure to create a wide-area network for remotely operating the stations and thus eliminate the need to support a separate or dedicated structure to accomplish the same. Another benefit of this configuration is that software updates for the functionality of the stations as well as adding and deleting stations will be done in the web server and may not require user intervention at the station when these tasks are performed. One potential disadvantage is that hackers may attempt to get access to the database since the network is accessible to almost anyone with a browser and access to the web. 
     An enhanced electronic key may be provided with additional hardware and software features to enhance the security, tracking, audit data control, and assisting of the employee to fill and service the vending machine.  FIG. 61  is a functional block diagram of the enhanced electronic key  6300 . The key  6300  has a microprocessor or microcomputer  6301 , a non-volatile memory  6302 , a real-time clock  6307 , and a battery  6312  for powering the components of the key. The memory  6302  may contain software and data required for the operation of the key, such as key codes, an encryption code for use in encrypting and decrypting communications with an electronic lock, encryption/decryption algorithms, backup clock data, power-up counter. The key memory may also contain data collected form vending machines, such as access audit data and vending machine inventory data. 
     The key  6300  includes a two-way communication module  6303  with a transceiver  6310  for two-way communications with the electronic lock  6299  of a vending machine. The key may also include user interface features  6304  such as a keypad, touch screen, or buttons with specific functions. An annunciation component  6305 , such as LCD screen, may be included for displaying key-lock responses, text messaging, email, etc. The key may include another two-way communication component  6306  that has a transceiver  6311  for communicating wirelessly with a home-base  6298 . 
     As a feature of the embodiment, the electronic key  6300  may further include a position sensing component  6308  for identifying the current location of the key. This component, which may include an antenna  6309  and may communicate with a location sensor, which may be internal or external to the key and may be based on one of the positioning systems such as GPS, DGPS, LORAN, etc. When an external location sensor is used, the component  6308  functions as an interface for receiving location information from the external location sensor. The external location sensor preferably has the capability to record time and location data independently of the key  6300 , and preferably is able to store an identification name or number to identify which user it is collecting data for. The data stored by the external location sensor may later be used as part of audit trail data for tracking and managing the field devices. 
     The advantage of including the position sensing system component  6308  in the key is the ability to track the location of each key used to access the vending machines. For example, electronic keys that include location tracking would pinpoint the geographical location of each vending machine the user of the key was attempting to access. Thus, and audit event for an access attempt would consist of the user of the key, the key code, the date and time of the attempt, the limits (if any) of the key, the serial or ID number of the vending machine, and the physical location (preferably at least 2-dimensional latitude and longitudinal coordinates, and possibly the third dimensional or altitude coordinate) of the vending machine being accessed. These coordinates could be translated by computer to common street address and location (for example, 100 W. Plainfield Rd, Countryside, Ill., second floor, suite 202). 
     When an electronic key has the capability of obtaining the location coordinates of a vending machine (either by receiving these coordinates itself by a position sensing system or by communication with a position sensing system at the vending machine location), the previously described step of reading the serial number of the vending machine (with a reader tool, or a bar code reading device, or by the electronic key) and entering the vending machine location data into the computer  5032  manually may be eliminated. Since the electronic key will produce or receive the location coordinates at the time it attempts to access the vending machine, this data can be provided to the database as the vending machine location in lieu of a manual entry, which is subject to human error. 
     An additional benefit of the position sensing feature in the electronic key  6300  is the ability to keep track of and/or locate keys if they are lost or stolen. Since this key has the data exchange feature described above, it can transmit its location coordinates to the central or home-base location or to a person possessing a computing device that would receive the location information. 
     An additional feature of this key  6300  is the data transfer capability. In additional to its capability of transferring data in short range to the docking cradle (as described for other keys in this system) this key may be equipped with the capability to transmit and receive data over longer distances. Thus, as a key is being operated the audit data and the vending machine sales and inventory data would be transferred back to a central or home-base location. The enhanced communication capabilities would include text messaging and email in order for the person using the key to send and receive information concerning the route they are working on, changes and additions, reports, etc. 
     In another implementation based on the embodiment described in  FIG. 61 , the electronic key  6300  utilizes the GPS position data to decide if it is enabled for operation. To that end, the electronic key  6300  includes additional registers or memory space, such as in the memory  6302 , for storing limiting parameters concerning the relative position of the key for deciding whether the key should be enabled or disabled. The position limiting parameters may, for example, specify the coordinates of areas in which the key  6300  is allowed to be used to access locks of vending machines. The position limiting data may be downloaded to the key  6300  during a refresh operation when the key is placed in the cradle of the key management system (e.g., at the bottling facility) as described earlier. Alternatively, the position limiting data may be received by the key  6300  wirelessly via the transceiver  6311  when the key is in the field. Besides the position limiting parameters, the memory  6302  of the key may store other access limit parameters, such as days of the week, number of days, number of access events, hours of the day, etc. 
     In operation, the GPS receiver  6308  receives position data indicating the current position coordinates of the key  6300 , and forwards the data to the processor of the key. The key  6300  compares the received position data with the position limiting data stored in it to determine whether the key is in a valid territory for operation as specified by the position limiting data. If the key is in a valid territory for operation, when key is actuated by the user, it will proceed with the unlocking operation, if the other operation limiting parameters are not exceeded. If, however, the key is not located in a valid territory, it will enter a disabled mode and cannot not used for accessing locks. If the key is later moved into a valid territory, it receives updated position coordinate data from the GPS receiver and determines that it is now in a valid territory, and returns to the enabled mode so that it can be used to access locks. 
     In accordance with a feature of invention, the concept of associating the location information with events of accessing a device in the field or controlling the operations of the device can be applied to various types of devices in different scenarios. One example of such an application is already described above in connection with the embodiment of  FIG. 61 , in which an electronic key  6300  is used to access a vending machine, and the location of the vending machine is one of the parameters used in determining whether the key should be allowed to open the lock of the vending machine. Other applications may involve field devices such as appliances, shipping containers, power tools, etc. As used herein, the term “appliances” includes vending machines, coolers, fountain drink dispensers, and other similar devices operated by AC power, DC power, or batteries. The types of operations of the devices to be controlled would depend on the particular devices. 
     By way of example,  FIG. 62  shows a fountain drink dispenser  6400 . In contrast to a vending machine, the fountain drink dispenser does not have openable door or closure guarded by a lock. Nevertheless, the dispenser  6400  has other functions and operations that can be controlled or enabled/disabled. 
     To that end, the dispenser has a controller  6401  that controls the functions and/or operations of the dispenser using actuator components such as motors, solenoids, relays, solid state switches, etc. The controller  6401  may be installed inside the appliance behind a surface wall of the appliance, or alternatively mounted on an outside surface of the appliance. The controller  6401  interacts with a mobile control device, which may be used to activate the dispenser at selected intervals. The mobile control device may be, for instance, an electronic key  6402  similarly constructed and programmed as the electronic key  6300  of the embodiment in  FIG. 61 . After being activated or enabled, the dispenser  6400  may work for a predetermined time period, such as one month, and then stop to be operational unless it is activated again by receiving an enable code from the key  6402 . For instance, the controller  6401  of the dispenser  6400  may be programmed to control the components of the dispenser such that the lights or the dispensing valves cannot be turned on, or the refrigeration unit does not operate to cool the drink to a regular temperature, unless it is enabled by the key. As another example, the appliance may require preventative maintenance and may turn on an indicator such as a “Maintenance Required” light  6405  after the machine has been in operation for a predefined period of time. In that case, the key  6402  can be used to turn off the indicator light and restart the service period when it visits the appliance. This arrangement allows the owner of the appliances in the field to track whether the appliances are properly maintained as required. 
     As illustrated in  FIG. 62 , when the electronic key  6402  is used to control the operations of the dispenser  6400 , the key establishes communications with the dispenser controller  6401 . As part of the communication process, the dispenser controller  6401  sends the device ID of the dispenser to the key  6401 . The key  6402  also obtains information regarding the current location of the dispenser  6400 , either before, substantially simultaneously with, or after receiving the device ID. The location information may be provided by a location sensor built into the key, or from an external location sensing device, such as a GPS receiver  6404 . When the key  6402  is actuated to communicate with the disperser controller  6401 , it also establishes communications with the external location sensing device  6404  to obtain the location data. Alternatively, the location information may be first transmitted from the external location sensing device  6404  to the dispenser controller  6401 , and then transmitted by the controller to the key  6402  as part of the communications between the key and the controller. In that case, the controller  6401  includes an interface  6406  for receiving the location data from the location sensing device  6404 . One significant advantage of using a location sensor that is mobile, instead of one with a fixed location or one installed in the field device being tracked, is that the mobile location sensor can travel with the key to visit field devices at different locations. Thus, one location sensor can be used to provide the location information for many field devices. This results in a significant reduction of cost as compared to having multiple location sensors in fixed locations or installed in respective field devices. 
     In a preferred embodiment, the location information may be used by the key  6402  to determine whether the dispenser  6400  should be enabled. For instance, the memory of the key  6402  may have stored therein allowed or valid location(s) of the dispenser  6400  associated with the dispenser ID. The key  6402  can compare the current location of the dispenser with the allowed location data in its memory to determine whether the dispenser is at a valid location. One aspect that makes this arrangement advantageous, as compared to storing the valid location information in the field device and using the field device to do the location validation, is that a person responsible for visiting the field devices is normally associated with a key, not a particular field device. Thus, this arrangement allows control of both (1) the assignment of the key to the employee, and (2) the location at which the key is allowed to access or enable a field device. 
     If the current location for the dispenser  6400  is valid, the key proceeds to enable the dispenser or otherwise control the operations of the dispenser. As used herein, “enabling” a field device means to give authorization to the controller of the field device to enable one or more functions of the field device other than the unlocking or locking of a closure such as a door. If the actual location of the dispenser is, however, different from the valid location stored in the key, the key may decide not to enable the dispenser. Preferably also as part of the communication process, the key  6402  may transmit its key ID to the dispenser controller  6401 . This allows the dispenser controller  6401  to learn which key is used to access it so that it can include that information in an audit trail record. The audit trail data concerning the control events, as well as other audit trail data concerning the usage of the dispenser over the last enabled operation period, can be downloaded to the key as part of the communication process. 
     The communications between the controller  6401  of the dispenser  6400  and the mobile control device  6402  may be wire-to-wire (i.e., through a cable connecting the dispenser controller and the mobile control device) or wireless (e.g., via RF or infrared transmissions). Non-encrypted communications may be used, but preferably encryption/decryption methods are used to protect the contents of the communications from eavesdropping. 
     When encryption/decryption is used to protect the communications, the communications may be performed according to the data flow diagram shown in  FIG. 63 . This flow diagram is generally similar to that shown  FIG. 23 , but with several additional steps performed in connection with location validation. Specifically, the memory  6132  of the key  6402  includes data representing the valid or invalid locations for one or more appliances in the field. When the user starts the communication process by pressing the button  6403  on the key  6402 , the key first reads and stores the current location data  6408  (step  6410 ). When the key receives the appliance ID from the controller of the appliance (step  6412 ), it stores the appliance ID with the location data as part of a control event record (step  6414 ). The key then determines whether it or the appliance is within the valid location for that appliance by comparing the actual location data with the location data stored in its memory (step  6415 ). If the appliance is outside its valid location, the key terminates the communication process (step  6416 ). As a result, the appliance may not be enabled for further operation. If, on the other hand, the appliance is in a valid location, the key continues with the communication process to ultimately enable the appliance (step  6420 ). 
     An alternative secured communication process for the key and the appliance is shown in  FIG. 64 . This data flow diagram is similar to that shown in  FIG. 24 , but with additional steps for location validation similar to those in  FIG. 63 . Again, when the user starts the communication process by pressing the button on the key (step  6422 ), the key first reads and stores the current location data (step  6424 ). When the key receives the appliance ID from the controller of the appliance (step  6425 ), it stores the appliance ID with the location data in a control event record (step  6426 ). The key then determines whether it or the appliance is within the valid location for that appliance based on the location data stored in its memory (step  6428 ). If the appliance is outside its valid location, the key terminates the communication process. As a result, the appliance may not be enabled for further operation. If the appliance is in a valid location, the key continues with the communication process to ultimately enable the appliance (step  6430 ). 
     In an alternative embodiment, the determination of whether the field device is at a valid location may be made by the controller of the field device, instead of the mobile control device. As shown in  FIG. 63 , the controller of the appliance may have the valid (or allowed) location data  6408  stored in its memory. To perform the location validation, the controller would require information regarding its current location. The controller may include an interface for receiving location data from a built-in location sensor or an external location sensor, such as a GPS receiver. Alternatively, the controller may receive the current location data from the key. To that end, the key may include the current location data  6421  as part of the encrypted transmission  6419  it sends to the appliance controller during the communication process. 
     In this optional arrangement, also shown in  FIG. 63 , the step  6415  of determining whether the location is valid is not performed by the key. Instead, it is now performed by the appliance controller (step  6418 ) by comparing the location data provided by the GPS sensor with the allowed location data stored in the memory of the appliance controller. If the location is valid, the controller enables the operation of the appliance. Similarly, in the alternative communication flow in  FIG. 64 , the current appliance location data  6421  may be transmitted to the appliance controller as part of the encrypted transmission  6430  to the appliance controller, and the step  6428  performed by the key to validate the location by comparing the current location with the allowed location is replaced by the step  6429  performed by the appliance controller. 
       FIG. 65  shows in a functional block diagram the circuitry for a controller  6401  that may be used to control the operation of an appliance. Even though the embodiment in  FIG. 65  is described as for controlling an appliance, it will be appreciated that it may also be used for controlling the access or operations of other types of field devices. The controller  6401  comprises a microcomputer  6450 , a non-volatile memory  6452 , a half-duplex IRDA infrared communication interface  6454  for communicating with an electronic key, a power supply voltage regulator  6456 , an appliance actuator control  6458 , an appliance operation actuator feedback  6460 , a learn switch  6462  similar to the one mentioned earlier in another embodiment, and the LED  6464  for state indication. The non-volatile memory  6452  stores key codes  6468 , encryption codes  6470 , audit data  6472 , and a device ID  6474  that identifies the appliance. The appliance operation actuator control  6458  may contain circuitry for controlling actuator components such as motors, solenoid, relays, etc., the actuation of which enables or disables one or more functions of the appliance. The actuator feedback  6460  provides feedback signals to the microprocessor for confirming the actuation states of the actuators. A clock  6465  provides time information so that the microprocessor  6450  can perform decisions such as whether the enabled operation period has expired and the machine should be disabled or whether the preventative maintenance indicator should be turned on. 
     The device control process performed by the controller  6401  of the appliance is generally illustrated in  FIG. 66 . The process starts at a state in which the appliance is enabled for normal operation (step  6480 ). The controller periodically checks whether the value in any of the limit counters or registers in its memory has exceeded a pre-defined limit parameter value (step  6482 ). The limit parameters include, for instance, the time period in which the appliance is allowed to operate. If no limit parameter has been exceeded, the controller returns to the state of normal operation. If, on the other hand, a parameter has exceeded its predefined limit value, the controller determines whether an enable code has been received (step  6484 ). If no enable code has been received, the controller disables the operations of appliance (step  6486 ). If an enable code has been received, the controller determines whether any request to modify limit parameters has been received (step  6488 ). If no, the controller resets the limit registers and counters (step  6490 ), and return to the normal operation state. If a request to modify limit parameters has been received, the controller modified the limit parameters as requested (step  6492 ). The controller then resets the limit registers and counters, and returns to the normal operation state. 
     As mentioned above, the collection and use of location data as part of a process of accessing or otherwise controlling the operations of a field device can be advantageously used in many different applications. A few more examples of such applications are provided below.  FIG. 67  shows a beverage cooler  6500 . The functions of the cooler, such as lighting and refrigeration, are controlled by a controller  6501 , the construction of which may be similar to that described in  FIG. 65 . An electronic key (or a mobile control device)  6402  is used to control the operations of the cooler  6500  by enabling or disabling the functions of the cooler. To that end, the key  6402  initiates a communication process with the controller  6501  of the cooler. As part of the communication process, the key obtains location data indicating the current location of the cooler. The location data may be received from an external location sensing device  6404 . Alternatively, the key may receive the location data from the cooler controller  6501  which in turn receives the location information from the external location sensing device  6303 . The key  6402  also receives from the controller  6501  the device ID for the cooler  6500 . If the key determines that the cooler is in a valid location, and other operation limit parameters are not exceeded, it transmits an enable code to the cooler controller  6501 , thereby enabling the cooler to operate for a pre-selected period, such as six months. As part of the communication process, audit data concerning the usage of the cooler may be downloaded from the controller  6501  to the key  6402 . 
     As another example,  FIG. 68  shows a container  6520  having a door  6522  or closure secured by a lock  6523  controlled by a controller  6521 . The container may be a safe, a tool box, or a shipping container, etc. The container  6520  may be placed at a fixed location, as in the case of a safe, or may be mobile as in the case of a truck-mounted tool box or a shipping container. A key  6402  is used to access the container to unlock the door  6522 . The key  6402  receives data representing the current location of the container from an external GPS receiver  6404  directly or indirectly through the lock control  6521 . The lock control  6521  transmits the lock ID to the key  6402 . Based on the lock ID and the currently location data and the permitted location data stored in its memory, the key  6402  determines whether the container  6520  is at a valid location. If the container  6520  is at a valid location, and other operation limit parameters are not exceeded, the key  6402  transmits an access code to the lock controller  6521 , which in response opens the door  6522 . 
     As a further example of a field device,  FIG. 69  shows a power tool  6530 , the operation of which may be enabled or disabled by a mobile control device such as a key  6402 . The power tool  6530  includes a controller  6531 , which is programmed to disable the power tool, such as by using a switch or relay to cut off power, if the power tool is not enabled. In the enabling operation, the key  6402  receives the current location from the GPS receiver  6404  and the device ID from the power tool controller  6531 , and determines whether the power tool  6530  is at a valid location. If the location is valid and other operation limit parameters are not exceeded, the key  6402  transmits an enabling code to the power tool. The tool controller  6531  than enables the power tool to operate, such as by allowing electrical power to be passed to the power circuit of the tool. Once enabled, the power tool  6530  may operate for a pre-selected period, such as 24 hours, after which it has to be enabled again in order to operate further. 
     Turning now to  FIG. 70 , in an alternative embodiment, instead of storing the location data for each access/control event in the key memory as part of the access/control event records, the location data may be stored in the external location sensing device and used later to reconstruct the event records. For instance, referring to the embodiment in  FIG. 62 , the key  6402  and the GPS receiver  6404  may be joined, such as being placed on a key chain, so that they travel together. Alternatively, the GPS receiver  6404  may have a fixed location, such as adjacent to the field device being tracked, or may be mounted to something that is external to the field device or the key and is mobile, such as a truck of the route operator. When the GPS device is mounted in a transportation vehicle, the GPS location might be limited to the location of the transportation vehicle instead of being the exact location of the appliance. 
     In another alternative embodiment shown in  FIG. 71 , the GPS receiver  6404  is normally plugged into a cradle  6560  in a transportation vehicle  6562  but can be removed from the cradle to allow it to be carried to the site of the filed device. Thus, if the reception of the GPS satellite signals at the site of the field device is good, the GPS receiver  6404  can provide the accurate location of that site. Otherwise, the location of the vehicle  6562  provided by the GPS receiver when it is received in the cradle  6560  can be used as an approximate position for the field device being visited. The cradle  6560  in the transportation vehicle  6562  preferably is configured for recharging the battery of the GPS receiver  6404 , and to enhance the reception of the GPS satellite location signals by connecting the GPS receiver  6404  to an antenna  6564 . 
     In operation, the GPS receiver  6404  records in its memory the location data and the actual (or real) time on a regular basis, such as every 5 seconds. Each time the key  6402  is used to communicate with an appliance such as a fountain drink dispenser, it stores the device ID of the appliance and the time of the control event, but not the location information, in its memory as a control event record. The key  6402  may be used to enable multiple dispensers or other appliances in a work day. When the key  6402  and the GPS receiver  6404  are returned to the home base at the end of a day, the control event records  6538  are downloaded from the memory of the key into the management station computer  6030 , as shown in  FIG. 70 . The location data  6540  as a function of time are also downloaded from the memory of the GPS receiver  6404  into management station. The management station  6030  then matches the timing of the control event records with the timing of the location records to identify the location for each control event. In this way, a complete control event record with location information can be reconstructed by the management station  6030 . This approach has the advantage of reduced complexity and cost of the electronic key and the GPS device, as they are not required to have respective communication ports to allow them to communicate with each other when the key is operated. Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. 
     Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.