Patent Publication Number: US-6211782-B1

Title: Electronic message delivery system utilizable in the monitoring of remote equipment and method of same

Description:
RELATED APPLICATIONS 
     This is a Continuation-in-Part application of U.S. patent application Ser. No. 09/317,235, filed May 24, 1999 and U.S. patent application Ser. No. 09/401,460, filed Sep. 22, 1999, and claims priority from U.S. Provisional Patent Application No. 60/115,305, filed Jan. 4, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to monitoring systems, and more specifically to networks for remotely monitoring the condition of devices such as those employed in heating, ventilating, and cooling (HVAC) systems. 
     2. Description of the Related Art 
     It is desirable to be able to monitor remotely equipment that may require periodic preventive maintenance and/or that may require rapid response time should a catastrophic failure occur. For example, the components of a building&#39;s HVAC system must be monitored or checked frequently. Preventive maintenance must be performed on a constant basis, particularly with larger systems. Fault or failure conditions may vary in degrees of severity, however the contractor responsible for maintaining the HVAC equipment should be made aware of each failure in due course. Since a contractor, in all likelihood, is responsible for the care and maintenance of the installations of multiple clients, and since fault conditions may occur at any time of day or night, it is not practical for a contractor to remain on-site all the time. Remote detection at a central location (for example, the contractor&#39;s office) of fault conditions is desirable and often crucial. 
     It is further desirable to be able to activate or deactivate a piece of equipment remotely or send it commands remotely. It is also desirable to know the approximate failure rate or frequency of failure of each piece of equipment. One can make installation recommendations as to which model or brand of equipment is best suited for a particular site, and one can anticipate the failure of an already-installed piece of equipment and specific components therein based on how long it is running. 
     Some remote monitoring devices have been developed. U.S. Pat. No. 5,629,687 to Sutton et al. describes a universal interface for remotely-monitored security or alarm systems. In Sutton et al., a local control unit at a monitored site can, under an event condition, initiate a telephone call to a central control unit to alert a human operator of an event such as an intrusion, fire, or other emergency at the site. The local control unit, via the telephone link, sends a serial number indicative of the specific site and emergency to the monitoring center computer. The monitoring center computer receives the serial number and alerts a human operator as to the emergency. The human operator can then act accordingly, e.g., establish one- or two-way communication with the local site. 
     U.S. Pat. No. 5,748,104 to Argyroudis et al. describes a wireless remote telemetry system which provides real-time reading and remote control of devices such as electricity meters. A home base unit communicates with remote metering units via cellular telephone lines. The home base unit also communicates with a central controller operated by the electric utility. When the utility determines that there is too much load on the power grid, for example, the central controller can send messages to an appliance to turn off. A customer could also remotely activate or deactivate an appliance via a cellular phone through the home base unit. 
     U.S. Pat. No. 5,061,916 to French et al. describes a system for remotely reporting, in graphical format, alarms or other conditions in a building&#39;s automation system. Sensors in a building are hooked up via a telephone line to control module which is, in turn, hooked up to a central controller. When a sensor detects a fault condition, graphical information is compiled at the central controller and transmitted to one or more remote facsimile machines. 
     All of the above systems and the prior art are limited in scope because they do not allow for sufficient flexibility in routing fault messages to a variety of different potential recipients of such messages via a variety of different media, depending on the urgency or nature of the fault. Also, the above systems and the prior art do not enable customers and contractors to enter or modify such information easily. As an example, a customer that has an HVAC system with a monitoring network may want to send certain non-emergency condition notifications (e.g., filter needs cleaning) to certain individuals (e.g., contractor/maintenance personnel) via a certain medium (e.g., e-mail) and emergency condition notifications (e.g., low or high refrigerant pressure) to other individuals (building owner, contractor, etc.) via other means (e.g., via beeper or other personal communication device). Such a list of who to contact via what means depending on which fault has occurred may be referred to as a “message profile”. The conventional device/contractor interface requires a dedicated land line at both the HVAC device and the contractor; that is, the HVAC system requires its own phone line, and the contractor must have a dedicated modem line as well. Moreover, the conventional system does not allow for easy customer modifications to the message profile. The conventional systems also do not allow the user to determine the failure rate of the equipment or to determine which pieces of equipment are best suited for a specific site. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment. 
     It is another object of the invention to provide a system for remotely monitoring multiple pieces of electrical and/or mechanical equipment in a cost-effective manner. 
     It is another object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment that can deliver messages to different individuals for different fault conditions. 
     It is another object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment that can deliver fault notification messages to different individuals for different fault conditions via different electronic media. 
     It is another object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment in which a customer may interactively modify its message profile. 
     It is another object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment in which a customer may interactively modify its message profile via the Internet. 
     It is another object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment in which a user may interactively alter the operation of a piece of equipment remotely. 
     It is another object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment in which the functional logic may be modified. 
     It is another object of the invention to provide a system for remotely monitoring electrical and/or mechanical equipment which can collect data over time concerning the monitored equipment. 
     The above and other objects are satisfied by the invention which is a remote equipment monitoring system and method for monitoring remote equipment. In the inventive method, the respective states of a plurality of parameters of at least one piece of remote equipment, such as heating, ventilating, and cooling equipment, are determined via a plurality of sensors. The information detected or gleaned from the sensors is grouped via ladder logic, preferably in the form of a programmable logic controller (PLC). Messages regarding the grouped information are communicated from the remote equipment to a central location as incoming messages. Outgoing exception messages are forwarded based on the incoming messages to at least one user-defined communication device. 
     The inventive system includes a plurality of sensors each monitoring a different parameter of the remote equipment. An interface unit is provided having a PLC connected to the sensors; the PLC performs Boolean expressions on signals received from the sensors and has a predetermined configuration. The interface unit also has a message generating mechanism. The system also includes a central computer server in communication with the interface unit adapted to receive messages generated by the interface unit. When the sensors detect an exception condition in the remote equipment, the PLC of the interface unit performs Boolean expressions on the signals in accordance with its predetermined configuration, and the interface unit generates an incoming exception message and forwards the message to the server. The server forwards at least one outgoing exception message to at least one predetermined user-defined communication device based on the incoming exception message. 
     The system can contact a customer or contractor via a number of different media (fax, email, pager, etc.) in case of an equipment failure. The contractor can determine which people to contact and which medium to use for which equipment failure. For example, if the condition is not very serious (e.g., filter needs cleaning), the contractor can set up the system to send a message via e-mail; if, however, it is serious (e.g., low/high refrigerant pressure), then the system can page the contractor and/or send a text message over his personal communication service (PCS). Also, the system includes the capability to send multiple messages to multiple recipients via differing media simultaneously for a given exception condition. Preferably, the system includes a centralized electronic message delivery device or server that routes the various incoming exception messages to the desired individuals via the desired electronic media in accordance with the predetermined message profile. More preferably, the contractor or consumer can access the centralized message server via the Internet and modify the message profile through software on the device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic of a preferred embodiment of a system according to the invention. 
     FIG. 2 is a schematic of a preferred embodiment of a link between the monitored equipment and the system according to the invention. 
     FIGS. 3 a-d  are schematics of links between an end-user&#39;s machine and the system according to the invention. 
     FIG. 4 is a schematic of a preferred embodiment of the electronic message delivery server according to the invention. 
     FIG. 5 is a flow chart depicting the operation of the system according to the invention. 
     FIG. 6 is a schematic of a local RF network linking several pieces of equipment together in accordance with an alternative embodiment of the invention. 
     FIG. 7 is a ladder logic diagram in accordance with the invention for an exemplary air conditioning unit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Equipment that needs to be monitored frequently, such as HVAC equipment, preferably operates within certain acceptable parameters. Some of these parameters are more crucial to the operation and/or life span of the equipment than are other parameters. For example, a low battery condition might be a lot less serious than a low coolant level condition. Whenever a piece of equipment operates outside its preferred parameters, an “exception” condition is created or said to exist. An exception condition can also be indicative of a regularly scheduled event occurring too often, too infrequently, or not at all. An exception condition could also be indicative of a measured value being beyond the design specification for the equipment. 
     When a monitored piece of equipment detects an exception condition, it activates its interface to the cellular phone network. The interface effectively acts as a cell phone in a roaming condition. The interface “attempts” to make a telephone call; because it is not recognized as being a resident of the local cell, the local cell (via the cellular network or mobile switching center) contacts the “home cell” of the interface to insure that the interface is in good standing to complete the “call.” There really is no home cell; in actuality, what is taking the place of the home cell of a cellular telephone is a message routing service such as those provided by Aeris or Bell South Cellemetry. When the local cell is contacting the message routing service, it transmits the following information: the serial number of the interface; the multi-digit “phone number” assigned to the interface; and the multi-digit phone number that the interface is “attempting to call.” The message routing service tells the local cell that the interface is okay and should not be blacklisted, that the call need not go through, and that the interface should be removed from the “okay to roam” list immediately. 
     The interface is not really trying to call anyone; the multi-digit phone number it was trying to call represents a multi-digit code of information that is being sent to the message routing service and may represent fault information (e.g., 212-555-1212 means “filter needs cleaning”). The phone number assigned to the interface (which is also sent along with the phone number it is “trying to contact”) may not only indicates which unit is doing the transmitting but may also convey fault information, since many of the devices being monitored do not have a large number of different fault conditions. This type of technology, in which information is transmitted in the handshaking portion of a cellular transmitter communicating to a local cell, appears in U.S. Pat. Nos. 5,594,740 to LaDue and U.S. Pat. No. 5,546,444 to Roach, Jr. et al., and is commonly referred to as using control channel data. In LaDue (the Aeris version), the exception or status information is embedded in the digits of the “phone number” the interface is allegedly calling (the “dialed digits”); in Roach, Jr. (the Bell South Cellemetry version), the exception or status information is embedded in the electronic serial number (ESN) of the interface, a number which identifies the physical hardware of the device. The information which identifies which interface has sent a message may be embedded in the mobile identification number (MIN) assigned to the interface unit. In the Aeris system, the ESN may also contain interface identification information. 
     The present invention expands on this technology and includes the message delivery technique mentioned above. The Aeris or Bell South Cellemetry router transmits the exception data to the inventive message delivery system which forwards the information to the contractor who is responsible for maintaining the faulty equipment. The contractor is provided with an account on the message delivery system that he can access via the Internet. The contractor sets up the specific parameters of which exception conditions are reported to which individuals. The contractor also sets up by which media (fax, e-mail, PCS) these individuals are to be notified. Multiple individuals may be alerted as to a exception condition. All of this data constitutes the contractor&#39;s message profile. For example, both the contractor and the owner of the premises might be signaled if there is a low/high refrigerant condition, however perhaps only one of them would be notified if a filter required cleaning. The user may also set, as part of the message profile, that different messages be delivered to different individuals at different times of the day, week, month, season, or year. For example, a high priority exception message may be directed to one repair/maintenance entity during regular business hours but be directed to a different repair/maintenance entity at night. Similarly, the same person could be contacted by different means (e.g., fax or PCS) at different times. The content of the messages may also vary as a function of time. 
     In addition to notifying contractors when a problem arises, the interface may be programmed to check in once a day with an “all systems okay” message. This “okay” message also gets routed to the message delivery system. However, instead of being handled by an exception message subroutine in the message delivery system—the portion of the system which handles the above-mentioned fault messages—, the “okay” message is checked by a missing message subroutine. The missing message subroutine checks the entire list of HVAC interfaces that are supposed to signal “okay” from the message delivery system database. The missing message subroutine compares the entire list to the list of HVAC interfaces that actually checked in as “okay”. If an interface failed to check in “okay”, the message delivery system sends out the appropriate messages to the proper individuals via the selected media, all in accordance with the user&#39;s message profile lodged in the user&#39;s account with the message delivery system. The periodic “okay” or status message is not merely limited to providing a status “heartbeat” for the equipment but may also be employed to transmit information about the monitored piece of equipment. As will be explained below, the status message only requires a portion of its digits to convey equipment identification information, thus allowing other information to be transmitted as well. For example, the status message may include statistical information about the equipment such as how many cycles it has performed since the last message, the run time of the motor, etc. The status message may also serve as a reminder for routine maintenance, or it may report very minor or low-priority conditions that are not time sensitive. 
     The format of the message sent from the failing device to the local cell to the router to the message delivery system is a multi-digit code. The first digit can be for message format (e.g., status message, exception message, etc.). The sub-address is a digit or two reserved to identify to which unit that a transceiver interface is assigned is experiencing an exception condition; i.e., one transceiver interface may be assigned to a building having nine HVAC units, all connected to the transceiver via a bus line, or one interface may be part of a local RF network where each of multiple HVAC units has its own transmitter. The final digits would indicate the specific exception condition. The multi-digit message received by the message delivery system is normalized, converted into a regular text message, and forwarded to the user/contractor. Information can also include model, brand, installation date, and climate and weather data for the site. Alternatively, much of this type of equipment criteria can be stored at the central data base so that only the equipment identification information need be transmitted. 
     A number of pieces of equipment may be linked to a single cellular interface via a local RF network. This is advantageous because many buildings have multiple pieces of HVAC equipment, and the provision of each piece with its own cellular interface is expensive. The deployment of a local RF network is also advantageous when the multiple HVAC units are fairly remote and a hardwired connection to a common bus line would be impractical or impossible. 
     Description will now be given of the preferred embodiments with reference to FIGS. 1-7. FIG. 1 shows an overall view of the inventive system  50 . An existing piece of equipment may be monitored, for example; an air-conditioner  2 , boiler  3 , motor starter  4 , heater  5 , or any other piece of equipment they may be desired to be monitored. The existing piece of equipment is fitted with an interface unit  10 . Periodically, the interface unit  10  sends to the message delivery server  1  a status signal to let the message delivery server  1  know that the equipment being monitored and the interface unit  10  are functioning correctly. When a predetermined exception condition occurs in the piece of equipment being monitored, the interface unit  10  sends an incoming exception message to the message delivery server  1 . The message delivery server  1  then routes the message as an outgoing exception message to the appropriate user interface; e-mail  6 , fax  7 , pager  8 , voice  9 , etc., according to the message profile as configured by the user of the system  21  via the Internet  122 . 
     The inventive system can be deployed on existing pieces of remote equipment. Various sensors can be added to an air conditioner, a boiler, etc. that can detect various conditions. For example, in an air conditioner, different sensors can be provided throughout the system each to detect a different condition such as low or high pressure, a condensate spill, air flow, fan motion, compressor function, etc. Any and all conventional sensors are contemplated as being usable in the invention, including but not limited to pressure sensors, pitot tubes, motion sensors, photosensors, electrical resistance sensors, moisture sensors, magnetic sensors, and the like. 
     Whether the sensors are built into the HVAC unit or added later, the various sensors in a monitored piece of equipment are preferably arranged in ladder logic configurations in programmable logic controllers (PLCs). Each sensor is responsible for detecting a certain condition or monitoring a certain parameter. These sensors can be grouped via Boolean logic operators (AND, OR, XOR, NOT, etc.) to provide the circumstances under which an exception condition is defined. 
     An example of such a ladder logic PLC for a typical air conditioning unit is shown in FIG.  7 . Each of sensors  602 - 609  monitors a different condition/parameter of the unit. Sensor  604  detects low pressure in the coolant, sensor  605  detects high pressure in the coolant, sensor  606  detects if the fan is working, sensor  607  detects if the compressor is working, sensor  608  determines if a condensate spill has occurred, and sensor  609  detects if the compressor is working. Some of the logic is direct and simple. For example, if sensor  605  detects a high pressure condition, high pressure message  101  is sent via the message generating mechanism of interface unit  10 . Similarly, if sensor  608  detects a condensate spill, message  102  is sent. 
     Other rungs of the ladder are more complex. For example, in line F, if sensor  606  detects that the fan is working, timer  1  is activated; if no air flow is detected by sensor  609  before timer  1  times out, the “no air flow” message  104  is sent. If, in line H, sensor  606  detects no fan operation and sensor  609  detects no air flow but sensor  607  detects proper compressor function, and timer  3  times out, “compressor w/no fan or air flow” message  105  is sent (line I). As another example, message  107  is sent out if sensor  602  detects a logic 0 in “aux 1” input and dip switch  4  is closed (logic 1) by activating relay  1  in line P. Alternatively, if sensor  602  detects a logic 1 in “aux 1” and dip switch  4  is open (logic 0), a message will be sent. In either case, a message  107  is sent in line O. 
     The dip switches are provided to allow certain portions of the logic to be disabled if a customer is not interested in receiving a certain type of message. For example, a sensor could be set to detect if a compressor is cycling fast and to send a “fast cycle” message in that event. However, if the user has the compressor deliberately set up to cycle fast, the user will not want to receive a constant stream of messages informing him that the compressor is cycling fast. Instead, a dip switch can be set to disable that message from being sent. The conventional dip switch is adjustable on-site. The invention contemplates also enabling the user to set up virtual dip switches via the Internet at a central server as will be explained below. 
     Each PLC can be different for each unit, type of unit, brand, model, etc. The PLC may by hard wired at the remote installation site. Alternatively, the various sensors can be linked via computer software at a web site that interacts with system  21 . For example, instead of sending out a low pressure message  100  for a low pressure condition and a high pressure message  101  for a high pressure condition, a user can OR the outputs of sensors  604  and  605  together for the sending out of an “abnormal pressure” message. A user can adjust a logic ladder in the same or similar fashion as one would edit a message profile, e.g., by menu-driven websites, by an automated telephone response system, etc. The user can, of course, request an initial hardwired configuration of the system installer and have that adjusted on-site as needed. 
     In FIG. 1, each piece of equipment  1 - 4  is provided with its own interface unit  10 . An alternative configuration is shown in FIG.  6 . As shown in FIG. 6, four air conditioners  2 A-D are each provided with sensor  600  (which generically represents any of sensors  602 - 609  and any like sensors) and an RF transmitter  601 . When an exception condition is detected by sensor  600 , or if after a certain period of time, no exception condition is detected, transmitter  601  transmits an RF signal  610  to a common interface unit  10 ′. Common interface unit  10 ′ includes antenna A for receiving signals  610 . Unit  10 ′ sends incoming messages to the electronic message delivery server  1  via link  11  in the same manner as shown in FIG.  1 . 
     Messages from some of the interface units  10  may be delivered by means of wireless transmission over the cellular telephone network (see U.S. Pat. Nos. 5,594,740 and 5,546,444). FIG. 2 is a detailed view of link  11  shown in FIG. 1. A message is transmitted from the cellular interface unit  10   a  via a radio frequency link  13  to a nearby cellular transceiver site  14 , the message is then routed to the cellular network or mobile switching center (MSC, e.g., a cellular carrier such as Bell Atlantic)  16  where the message is then delivered via data circuits  17  and via router  51  (e.g., Bell South Cellemetry or Aeris) to the message delivery server  1 . As will be clear from the discussion of FIG. 4, reference numerals  11   a  and  11   b  refer to different types of links. Specifically, link  11   a  is for receiving incoming exception and status messages from interfaces  10  which are in regions wired for sending data via the dialed digits control channel; link  11   b  forwards messages along the ESN channel to the message server  1 . 
     Based on the configuration of the user&#39;s message profile, the outgoing exception message (or messages) is then delivered to the specified end device or devices. FIGS. 3 a-d  show a more detailed view of the various outbound links  12   a-d  that connect the server  1  to the various electronic media. In FIG. 3 a , server  1  sends the message over a telephone line  18   a  to the Internet  122  and deposits the message in the user&#39;s e-mail box  6 . In FIG. 3 b , server  1  sends the message over a telephone line  18   b  through the public telephone switched network (PTSN)  19  to the user&#39;s fax machine  7 . In FIG. 3 c , server  1  sends the message over a telephone line  18   c  to the user&#39;s pager service  53  and thence to the user&#39;s pager or PCS  8 . In FIG. 3 d , server  1  sends the message over a telephone line  18   d  through the PTSN  19  to the user&#39;s voice mail box  9 . The same message may also be sent to a number of other devices as configured by the user  121  over the Internet  122 . The same message that is being sent to a fax machine  7  as described above may also simultaneously be sent to an e-mail  6  recipient via the Internet. Preferably, different messages can be sent to different individuals simultaneously for the same fault condition; for example, the owner of the premises may receive a less-detailed message than the contractor. 
     A user&#39;s message profile can also be configured to store messages on server  1  for delivery at a later time or after certain conditions are met. For example, a contractor may not want his beeper activated every time server  1  receives an incoming exception message. The user profile can be configured to deliver messages on groups or only after several messages have accumulated for the same user/contractor. Optionally, an outgoing exception message may be generated only after several of the same type of incoming message are received; a portion of the memory of server  1  may be devoted to the storing and/or accumulating of messages. Alternatively, a single outgoing exception message may be generated in response to several incoming messages. 
     In the same way the user profile can be configured, the user can configure virtual dip switches to enable or disable certain error messages. Conventional hardwired dip switches must be adjusted on site at the remote equipment. Virtual dip switches are software subroutines stored in server  1  which allow the user to toggle on or off certain portions of the ladder logic of the PLCs controlling the sensors of the remote equipment. According to the invention, the user can go to a website on the Internet  122  and, through menu-driven commands, enable or disable sections of the ladder logic just as he would be able to by flipping conventional dip switches at the installation site of the remote equipment. Additionally, the user will be able to configure the logic of the PLC remotely via the Internet as well. 
     A user may also control the functioning of a remote device in this way, via the Internet. The user can enter commands at the website or other Internet interface, and those commands are forwarded to the server  1 . In accordance with the user profile, for example, in the same way that exception messages are sent out via links  12   a-d , a command message may be sent to the remote device through interface unit  10 . Such command messages allow the user to activate, deactivate, and otherwise control the appliance. The interface unit  10  can receive these command messages because the means by which the unit  10  communicates with the server, e.g., the cellular telephone network, is bi-directional. As a result of this bi-directionality, incoming links  11   a-d  may also be used to communicate with the devices through their respective interface units  10 . 
     FIG. 4 shows the details of the message delivery server  1 . In the preferred embodiment, server  1  includes four hardware devices  200 ,  300 ,  400 , and  500 . Device  200  is responsible for receiving incoming messages, processing them in accordance with the user&#39;s preferences, and routing them for output. Messages may be temporarily stored or accumulated on device  200  before being transmitted to the user if the user&#39;s message profile is set up accordingly. Device  300  enables the user  121  to access server  1  and create or edit his message profile residing in relational data base  21  of device  200 . Device  400  includes the various drivers  33  which are responsible for transmitting the various messages to the various media (fax, e-mail, etc.). Device  500  includes billing computer  38  for keeping track of the charges and fees associated with the user&#39;s use of the service. 
     At the core of server  1  is a relational data base  21 . Incoming messages are received by a specific service designed to handle both the transport method and message formatting. Every interface unit  10  is provided, like a cellular telephone, with an electronic serial number (ESN, to identify the specific interface unit sending the message) and a mobile identification number (MIN, similar to a cellular telephone&#39;s phone number). In some instances, the exception or status information is embedded in the dialed digits the interface transmits. The dialed digits control channel module  25  specifically receives messages that are encoded in the control channel&#39;s dialed digits (see U.S. Pat. No. 5,594,740). The ESN control channel module  24  receives messages that are encode in the electronic serial number of the message (U.S. Pat. No. 5,546,444). It is preferable to have both a dialed digits module  25  and an ESN module  24 , because some geographic regions employ dialed digit data coding, while other regions employ ESN data coding. Information may be transmitted via the MIN of the interface  10  and also received by message delivery server  1 . Services are also available to receive messages for analog modems connected to the public telephone switched network  23 , and the cellular digital packet data network  22 . As additional methods of transmitting data become available, they can be added to the services layer. 
     All incoming messages are normalized at the normalization module  26  so that all incoming messages can then be processed without regard to their incoming medium. All incoming messages are passed to the normal message subroutine  27 , exception messages are passed on for processing and routing via the user&#39;s configuration through the data base  21 , and periodic status messages are queued. The missing message subroutine  28  compares received status messages with a list of expected messages. Status messages that are not received have an error message generated by the missing message subroutine  28  which are then delivered as configured by the user in his message profile as recorded in the relational database  21 . 
     Messages to be delivered are placed in a message queue  32 ; as message traffic permits the appropriate drivers  33  request messages from the message queue  32  and route the messages over the appropriate transport. Numeric pages, faxes, voice and DTMF  34  are sent over the PTSN  12   b-d , e-mail  35  is sent over the Internet  122 . When a driver  33  has successfully delivered, a record is made in the data base  21  by the delivery confirmation subroutine  31  showing time and date of successful deliveries. Undeliverable messages are routed back to the database for generation of undeliverable message errors. 
     Users  121  connect to an Internet information server  30  via the Internet  122 . The Internet information server presents to the user the information pertaining to that user&#39;s interfaces. Requests to alter the user&#39;s data are passed through active server pages  29  to protect both the integrity and security of the data base  21 . All messages and transactions that pass through the system are logged in section  36 , the transaction and message logs are then interfaced by section  37  to a billing system  38 . 
     A portion of the memory in relational data base  21  is preferably used to compile data regarding the devices being monitored over time. Such data is sortable by any number of different criteria, including brand of equipment, specific models of equipment, installation date (and thus the age of the equipment), the general local climate in which the equipment is installed (e.g., arid, humid, warm, rainy, etc.), local weather conditions in a given period of time, and the like. This information is usable in a number of different ways. A user can log in via the Internet, for example, and find out the maintenance history of his specific units to see which are the most reliable or most unreliable. Alternatively, a user can check to see which brands or models generally are the most reliable for any given conditions (age, climate, weather, etc.). Additionally, the information may be collated and processed by the operator of data base  21  and published by any number of different criteria. Any of the various messages may be stored for this purpose, e.g., the incoming messages from the interface units, the normalized messages output from the normalization module, the outgoing messages, normal status messages, etc. 
     An example of the system&#39;s operation is as follows. When a user-contractor  121  first signs up with the system  50 , he receives an account on the electronic message delivery server  1 . Via the Internet, the contractor  121  is prompted through software to enter the pager numbers, cellular telephone numbers, facsimile machine numbers, and Internet addresses of any individuals who are to be contacted in the event of an exception condition in building equipment  2 - 5  for which the contractor is responsible. The user-contractor  121  may also set the software to notify him of the periodic successful routine status check messages conveyed from equipment  2 - 5 . 
     FIG. 5 depicts a flow chart of the basic steps that occur when a message is received by server  1 . At step S 1 , the message is received. At step S 2 , normalization module  26  removes the required elements from the incoming message and arranges them in a normalized format and stores them as a record in a table. Server  1  can now examine a specific element in a message of any received media type. At step S 3 , it is determined what type of error message has been received. If it is an exception message that requires immediate action, it is passed onto a process to begin configuration of a readable message at step S 4  for delivery at step S 5 . If not, server  1  determines if the received message is a “unit checking in” or a “system ok” status message at step S 6 . If the user has his message profile so configured, a storing/accumulating step (not shown) may occur between steps S 4  and S 5 . Undefined messages are handled at step S 7 . If it is configured as a periodic message received to indicate normal operation of a unit, the message is stored at step S 8  for use at a later time. Periodically, the list of units that have reported in at step S 8  and the list of active units expected to report in (part of database  21 ) are compared at step S 9 . Units on the active list that do not appear on the checked-in units list are processed, and units that failed to report in have messages created at step S 10 . These messages are then posted for further processing and message delivery at step S 5 . 
     In the example given, suppose boiler  3  breaks down in a non-catastrophic manner. The fault condition is detected by a sensor (not shown) and encoded to interface  10 . Interface  10  transmits a radio message via link  13  to a local cell site  14 , which contacts data circuits  17  via cellular network  16 . Circuits  17  forward the message to message server  1 . If the message is transmitted by the cellular telephone network  16 , the ESN arrives via link  11   b  to ESN channel  24 ; alternatively, the dialed digits information arrives via link  11   a  to dialed digits channel  25 . The message is normalized in normalization module  26  and passed along to the normalized message process module  27 . Module  27  selects the user&#39;s message profile from relational database  21  and in accordance therewith, determines what message gets sent to whom and by which medium. Alternatively or in addition, multiple fault conditions may be linked together via user-configurable ladder logic. 
     The invention is not limited to the above description but rather is defined by the claims appearing hereinbelow. Modifications to the above description that include that which is known in the art are well within the scope of the contemplated invention. For example, the invention is designed to be adaptable to all forms of electronic communication, be they cellular telephone, land line telephone, electronic mail, facsimile, text page, voice mail, etc. All forms of electronic media are contemplated as being within the scope of the invention. Also, multiple formats of incoming and outgoing messages are contemplated as included within the scope of the claims and the invention. The user can adjust the format and content of the messages he receives by setting up his message profile accordingly. The invention is also not limited to use in monitoring HVAC equipment but is contemplated to be useful for maintaining all forms of remote equipment. For example, the inventive system and method would prove extremely expedient is monitoring and replacing warning lights on cellular towers, radio transmitter towers, and other remote structures.