# Patent

## Title
Variable group communication system

## Abstract

A flexible multi-processor communications system supports variable message lengths and variable groups and application designations at respective processors. The receiving processors determine what action, if any, needs to be taken in response to the combination of group and application information in the messages. The receiving processors can include pluralities of pre-stored groups and applications along with associated priorities and the functions to perform.

## Background
This application is a divisional of U.S. Ser. No. 09/211,546 filed Dec. 15, 1998, now U.S. Pat. No. 6,691,172 B1.


FIELD OF THE INVENTION
This invention pertains to multi-processor communications systems. More particularly, the invention pertains to such systems wherein processors can be grouped in different ways.
BACKGROUND OF THE INVENTION
Multi-processor communications systems particularly for use in monitoring a region or regions are known. One particular form of such a system is disclosed in Tice et al U.S. Pat. No. 5,525,962 entitled Communication System and Method assigned to the assignee hereof and incorporated by reference. Another such system is disclosed in Tice et al U.S. Pat. No. 4,916,432 entitled Smoke and Fire Detection System Communication, also assigned to the assignee hereof and incorporated by reference.
Known systems, while effective for their intended purpose, have exhibited some limitations. Typical systems usually have preset message lengths which are not field programmable. It would be desirable if the flexibility of such systems could be enhanced by providing field programmable, message lengths. Such flexibility would take into account newly developed formats, improvements or features which are intended to be field installable or field upgradeable.
SUMMARY OF THE INVENTION
A flexible multi-processor communications system makes use of multiple prestored groups and applications. In a peer-to-peer type system, each transmitting processor transmits group and function information. This arrangement facilitates communications between a transmitting and receiving device.
In an alternate configuration, a transmitting device does not have direct access to group information. Instead, group information is provided by a common communication device in response to a message from a transmitting device.
The grouping information that is transmitted with the device messages specifies its membership with other devices. The membership or grouping can be changed as a function of the type of message that is being transmitted. This can allow different functional relationships.
For alarms, devices may be grouped so that smoke control is achieved with one grouping and annunciation is achieved with a different grouping. Door control devices could be grouped separate from smoke control or annunciation.
The different groupings can be achieved by including them at one time in a message or by transmitting separate messages specifying the different groups and the different functions. Examples of multiple groups include: 1) smoke control groups, 2) annunciation groups, 3) door lock groups, 4) lighting control groups, 5) ventilation control groups, and 6) fire suppression groups.
Devices can be loaded with information specifying multiple groups to which each respective device is assigned. In addition, each device can be loaded with application or function related codes that specify different applications (i.e. fire, security, HVAC, etc.).
Although the receiving devices are loaded with group and application programs, they are not yet “bound” to the transmitting devices. Transmitting devices, in one disclosed embodiment will broadcast their information with application type and individual address. The receiving devices will record the broadcast but not be able to determine how to function until another processor, such as a common control element, adds additional information to the system.
The common control element will dynamically make the group decisions based upon the transmitting device, effectively binding the transmitting device into a group. This process is dynamic and the same transmitting device may become a member of a different group based upon prior events. The type of device transmitting a state change is therefore linked to specific other devices by both the application type and group memberships, as defined by the common control element.
In an alternate or peer-to-peer system, there is no common control element and the transmitting device inserts the group numbers into the message. The transmitting message may contain multiple group numbers and/or application type numbers. The receiving devices may be programmed with multiple group numbers.
In both of the above systems, the devices are programmed with multiple groups and/or multiple applications. A particular system 1) may contain only one group and multiple application codes, or 2) may contain one application code and multiple groups or, 3) may contain multiple groups and multiple application codes.
The grouping can be dynamic in that the action can be different and dependent upon previous messages communicated on the system. If one group is in a predetermined state, then the grouping can be changed so that at least some devices are now members of different groups than originally programmed. The common control element can determine this new relationship between transmitting devices and receiving devices. New group numbers can also be downloaded to devices in real time during system operation to establish different operating groups dynamically and quickly.
In yet another embodiment, a multi-processor communication system having variable grouping exhibits enhanced flexibility by providing a communications protocol with programmable message lengths. In one aspect, a command can be sent to one or more processors specifying subsequent message lengths as an integer number of bytes.
The command can be transmitted separately or in conjunction with a message being transmitted. The lengths of messages being transmitted to one or more processors and the length of messages being received from one or more processors can be programmed independently of one another.
Message priorities can be programmed to reassign message priorities dynamically in response to changing conditions. In one embodiment, a first byte of a message can be assigned a priority indicating function.
In addition to establishing a priority for transmission, an execution priority can also be established by the priority byte. In this regard, transmission priority can be established independently of execution priority.
As a result of separating message content from transmission or execution priority, some copies of a message can be immediately transmitted to selected processors for immediate execution. Other copies of that message can be transmitted with a much lower priority to different devices.
In order to enhance message integrity, the location of a check sum or other error checking code can be specified during transmission to the receiving device or devices. The receiving device or devices can then extract the check sum or error checking code from the specified location in the message. The integrity of the received message can then be evaluated.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the system in accordance with the present invention;
FIG. 2 illustrates schematically a plurality of messages having different, programmed, lengths;
FIG. 3 is a flow diagram illustrating message processing;
FIG. 4 is a tree illustrating programming of devices based on application type then group type;
FIG. 5 is a tree illustrating programming of devices based on group type then application type; and
FIG. 6 is a flow diagram illustrating reading a selected byte of a message and using the contents of that byte to interpret the rest of the message.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
While this invention is susceptible of embodiment in many different forms, there are shown in the drawing and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated.
FIG. 1 illustrates a multi-processor communication system 10 which can be used for monitoring a plurality of conditions in one or more regions to be supervised. The system 10 includes an optional common control unit 12 which could be implemented as one or more interconnected programmed processors and associated, prestored instructions.
The unit 12 includes an interface for coupling, for example, to a communications medium 14, is illustrated in FIG. 1 for exemplary purposes only as an optical or electrical cable. Alternately, the system 10 can communicate wirelessly, such as by RF or infrared, via transceiver 16, illustrated in phantom in FIG. 1, and antenna 16a. 
Coupled to medium 14 is a plurality of ambient condition detectors 18, such as device 18n, and a plurality of control or function units 20, such as device 20p. It will be understood that the relative arrangement of the members of the pluralities 18 and 20 relative to the medium 14 is not a limitation of the present invention.
The members of the plurality 18 can include intrusion sensors, position sensors, gas sensors, fire sensors such as smoke sensors, thermal sensors or the like, and gas sensors all without limitation. The members of the plurality 20 can include solenoid actuated control or function implementing units, audible output devices, display devices, printers or the like.
Where system 10 incorporates a wireless communications medium, a plurality 22 of wireless units or devices could be in bidirectional communication with each other and with transceiver 16. The plurality 22 can include, without limitation, ambient condition detectors, as noted above as well as control or function implementation devices without limitation.
One exemplary form of the device 18, 20, 22 of FIG. 1 is disclosed in U.S. Pat. No. 6,326,880. That patent has been assigned to the assignee hereof and is incorporated by reference.
Also coupled to the control unit 12 via a medium 24, illustrated for example as a pair of electrical cables, is a plurality 26 of output devices. These could include audible or visible output devices without limitation, speech output devices and the like. The devices 26 are intended to broadcast a message, which might indicate an alarm condition, in one or more predetermined regions.
System 10 provides an enhanced level of flexibility and upgradeability by supporting variable length message formats. Message lengths can be altered in the field after installation.
FIG. 2 illustrates several messages each of which has a different, preprogrammed, length. Message No. 1 has been preprogrammed to have a length corresponding to four data bytes. As illustrated in FIG. 2, a check sum is transmitted in the fourth byte of message No. 1.
Message No. 2 has been preprogrammed for a length corresponding to seven data bytes. In message No. 2, illustrated in FIG. 2, a check sum is transmitted in both byte No. 3 and in byte No. 7.
Message No. 3 of FIG. 2 has been programmed to have a length corresponding to two data bytes. In message No. 3, the check sum is transmitted in the second byte.
With respect to the various lengths of messages illustrated in FIG. 2, a predetermined location for a check sum can be downloaded to the various devices of the system. Hence, in addition to being able to program different message lengths, the location of the check sum byte is also programmable.
A separate message length setting command can be transmitted from a selected device in the system 10 or from the control element 12. Similarly, information pertaining to the location of the check sum can be downloaded from a selected device in the system 10 or the control element 12.
A selected byte or bytes of a received message can specify the location of the error checking codes, such as a checksum, in the received message. In addition, that byte or bytes can include additional information, such as message type or format usable by a receiving device, illustrated in FIG. 6.
Priorities can be assigned to messages to be transmitted from devices on the system 10. For example, the first byte of a transmitted message can carry the assigned priority for that message. This byte can determine not only transmission priority but also an execution or action priority of a message received at a device, such as device 20p of system 10.
A higher priority message transmission will be carried out by a transmitting device or transmitting control element before lower priority messages are transmitted. In addition, the action or function represented by a higher priority message will be carried out or take precedence over lower priority messages.
As those of skill in the art will understand, a system in accordance herewith makes it possible to reassign message priority, as well as execution priority, independent of message content. Hence, the same message content can be transmitted with various transmission priorities and various action or execution priorities. In an instance where the system 10 corresponds to a region monitoring system such as a security system or a fire alarm system, different messages can be assigned different priority levels based on the type of functionality involved.
A receiving device or devices use a message's priority level to determining if a message should be carried out or executed.
For example, a security device may want to turn a device A to an on-state and a fire device may want to turn the same device A to an off-state. If both the security device and the fire detector transmit commands to the device A at the same time, device A has to give one a higher priority than the other to resolve the commands. This decision can be made based on the priority information.
The higher priority message will be executed first by device A. Once a message has been executed, the respective device will only execute a new message if it has a higher priority.
For example, a security message can command a door to lock. However, if fire is assigned a higher priority than security, a fire message can command the door to unlock, thus overriding a security message. A subsequent security message will not cause the door to lock again until the door is reset from the fire state. However, if it is subsequently determined that an HVAC message should be assigned a higher priority than a fire message for control purposes that higher priority information can then be attached to the HVAC message. Upon receipt of this higher priority message, the door device will respond to the HVAC message, overriding the earlier fire message.
FIG. 3 illustrates exemplary processing 100 in accordance with priority levels. In a step 102, the presence of a received message has been detected.
In a step 104, the priority information is extracted from the received message. In a step 106, the priority level of the received message is compared to the highest previously received priority level. If the priority level of the received message is less than or equal to the highest priority previously received, no action is taken.
If the priority of the received message exceeds the priority of the previously received message, the priority of the received message is stored in a step 108 and that message is responded to or executed in a step 110. Thus, contention between newly received messages or between a newly received message and all messages received since the device had received a reset command will always be resolved in favor of the highest priority received message.
System 10 has for exemplary purposes only, been described in the context of a monitoring system. Those of skill in the art will understand that the invention has applicability to multi-processor communication systems which exhibit other types of functionality as well.
The members of the pluralities 18, 20 or 22 preferably include programmed processors. The processors can be downloaded with group and application programs.
In one aspect, the type of application specifies a plurality of groups stored at the respective processor. In another aspect, the type of group specifies a plurality of applications which are stored at the respective processor.
Devices which need to initiate an activity or action will transmit a message on the respective wired or wireless medium. Typical broadcast information includes application type and address.
Where each of the members of the pluralities 18, 20, 22 stores its respective group and application information, the transmitting device will provide the group number or numbers as part of the communication. The transmitted message may contain multiple group numbers and/or application specifying identifiers.
In an alternate embodiment, a common communication device, in response to receipt of a message from a transmitting device, will retrieve from a central data base group and application information which is then broadcast throughout the media to complete the transmission initiated by the transmitting device.
The common control device can dynamically select groups based upon the message received from the transmitting device thereby binding the transmitting device to a group. The dynamic nature of the process is such that a single transmitting device may become a member of different groups based on prior events.
The devices in the system can be programmed to contain a single group and multiple application designators. Alternately, the devices may contain a single application designator and multiple group designations. Finally, the respective device may contain both multiple group designations and multiple application information.
FIG. 4 illustrates processing and a programmed tree associated with one or more of the devices of the pluralities 18, 20 or 22. In the embodiment of FIG. 4, in response to having received a message in a step 100, the priority of that message is evaluated, as discussed above, in a step 102. Assuming that the message is to be executed, as a result of its priority, an application designation is extracted from the message and compared to a plurality of prestored applications. The matching application is selected.
A transmitted group number, associated with that particular application, can then be compared to a plurality of prestored groups. In a step indicated generally at 106, for Application 2, in response to having identified either a matching group number or no match, a specified action is carried out. Hence, as illustrated in FIG. 4, depending on a received Application specifier and a received Group specifier, a given device can initiate or carry out a variety of different actions.
Representative actions include, without limitation, sounding verbal or audible alarms, energizing or de-energizing circuits in illumination systems, energizing or de-energizing ventilation systems, energizing or de-energizing door access systems or the like. Hence, by changing transmitted application designation and transmitted group number, a selected device will be able to carry out a plurality of different functions.
FIG. 5 illustrates alternate processing steps and a tree which can be stored in a respective device. As indicated generally at 112 in response to having received a Group 2 representation from the medium, a plurality of different actions or activities can be selected based on a transmitted application designator. If desired, respective devices could store both types of selection trees depending on the nature and complexity of the respective device.
As a result of the above types of structures and processes, the respective devices can include multiple applications and can be members of multiple groups. This, of course, promotes versatility.
Group and application information can be downloaded to the respective devices when manufactured or installation. Both group and application designations can be changed in the field if needed.
The processing structures of FIGS. 4 and 5 provide a form of dynamic operation wherein the actions taken by a particular device can vary and be dependent upon previous messages communicated throughout the system. If desired, grouping and or function designations can be dynamically changed in real time. The revised group and function information can be stored at a common location and provided in response to transmitted messages. Additionally, group and application or function designation information can be downloaded to devices in real time to thereby establish different operating groups dynamically and quickly.
Byte 1 of the message contains the communication access priority for the message. If the message has a higher priority, it will be communicated on the medium before other lower priority messages.
An improvement in the prior art is that Byte 1 is variable and can be reassigned based upon the conditions present in the system. If the system is in a state where the common control unit needs priority in communications, it can assign itself a higher priority in Byte 1 and have priority access to the communications media. A device can also be programmed with a first priority but that priority can be changed to change its access priority to the communications media. For example, if a device sends a message and the message is not received without errors by another device, that device or other devices may repeat that message over and over but at a lower priority such that it still attempts to communicate the original with a predetermined device but does not interfere with other devices transmitting high priority information. Alternately, a device can be downloaded with a new priority to reflect the new conditions in the system. a communication from a common control unit to an annunciation device may initially have a low priority but then be changed to a higher priority once alarms are detected to the system.
The system is therefore dynamic and can change the priority of the devices in the system for communication access. The priority byte can be determined by a downloaded priority or a predetermined sequence of priorities as a function of the system condition. The priority can be automatically determined in the devices based upon a selection from a plurality of priorities stored in the devices.
From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.

## Claims

1. A multi-processor communication system comprising:
a communication medium;
a plurality of processors, coupled to the medium, where the processors are capable of transmitting and receiving messages from the medium wherein the messages contain priority information for priority access to the communication medium and wherein the priority information can be changed dynamically dependent upon at least one previous condition in the system; and, where a receiving processor compares a priority level of a received message to a highest previously received priority level, and executes the received message only if its priority level exceeds that of the highest previously received priority level.

2. A system as in claim 1 wherein the priority information can be changed by a common control unit coupled to the medium.

3. A system as in claim 1 wherein the priority information can be changed by the transmitting unit itself.

4. A system as in claim 1 wherein the previous conditions in the system are determined by monitoring the communication messages in the system.

5. A system as in claim 1 wherein previous conditions include previous operating states of other devices in the system.

6. A system as in claim 1 wherein previous conditions comprise previous priority information transmitted on the system.

7. A system as in claim 1 where the receiving processor in executing the message extracts an application identifier therefrom and, responsive to the presence of an identified application at the processor executes that application.

8. A system as in claim 7 where the receiving processor also extracts a received action identifier from the message.

9. A system as in claim 1 where the receiving processor in executing the message extracts a group identifier therefrom, the group identifier associates the receiving processor with other processors.

10. A system as in claim 9 where a receiving processor selects one of a plurality of applications in response to an extracted group identifier.

11. A system as in claim 9 where groups are selected from a class which includes at least smoke control groups, fire suppression groups, annunciation groups, door control groups, lighting control groups, and ventilation control groups.

12. A system as in claim 1 where members of the plurality of processors include circuitry selected from a class which includes fire sensors, thermal sensors, smoke sensors, gas sensors, intrusion sensors, function implementing circuits, audible output devices and display devices.

13. As system as in claim 11 where members of the plurality of processors include circuitry selected from a class which includes fire sensors, thermal sensors, smoke sensors, gas sensors, intrusion sensors, function implementing circuits, audible output devices and display devices.

14. A system as in claim 12 where the messages include a size parameter and information in accordance therewith.