Abstract:
A method of supervising a plurality of displaced devices includes having each device emit a supervisory signal that is detectable by a designated unit. Indicia can be included indicative that an intervening message has been sent from a respective device. The designated unit can respond to missing, expected supervisory signals as well as unreceived messages.

Description:
FIELD 
   The invention pertains to systems and methods to supervise the operation of other devices. More particularly, the invention pertains to such systems and methods where the devices periodically emit condition indicating signals. 
   BACKGROUND 
   Various types of monitoring systems such as fire or gas alarm systems, built-in control systems, security systems and the like carry out functions which preferably can be relied on to provide warnings relative to developing conditions which are in need of attention. It has been recognized that it is desirable to supervise the function of the components of such systems to minimize the likelihood that one or more portions of such systems might fail and not give any indication thereof. For example, where the systems are configured as networks of devices, it would be desirable to know if any transmitted messages were not received, or, if a respective device or devices had malfunctioned in some way. It would also be desirable to incorporate supervision capabilities which can be carried out automatically on an ongoing basis without substantially adding to the cost or complexity of such systems. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of a system which embodies the invention; 
       FIG. 1A  is a block diagram of a device usable in the system of  FIG. 1 ; 
       FIG. 2  is a flow diagram of processing at a device being supervised; and 
       FIG. 3  is a flow diagram of processing at a supervisory unit usable in the system of  FIG. 1 . 
   

   DETAILED DESCRIPTION 
   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. 
   Processing methods in accordance with the invention couple periodic messages from remote devices to one or more supervising devices. The messages are transmitted at predetermined, fixed time intervals. Such processing enables one or more supervising devices to determine if an event message from one of the remote devices has not been received. Further, the processing enables the receiving devices to determine when they are no longer receiving messages from one or more remote devices. 
   In one aspect of the invention, remote devices transmit a first message to at least one supervising device. The first messages are spaced apart by predetermined time intervals. Thus, both the remote devices and the supervising device transmit and/or receive the first messages with spaced apart durations or predefined periods. 
   Each of the first, or “ping”, messages will include at least a first message sequence identifier. Event messages from one or more remote devices indicative of one or more sensed conditions will be transmitted to the supervising device or devices with second or event sequence identifiers. Further, each of the first messages can incorporate an event or a second message sequence identifier. Other status or condition indicating information can be included in the ping messages. 
   In yet another aspect of the invention, the identifier of the first and second messages can be represented as numeric values. Initially, the first and second message identifiers can be set to a value of zero when the respective device is reset. 
   If a supervising device has not received either a first message or a second message from respective remote devices within the predetermined period or time interval, the supervising devices can determine that the respective remote device may not be functioning properly. Audible as well as visual indicia can be provided indicative thereof. 
   In yet another aspect of the invention, the identifier for the initial ping message from a remote device can be transmitted having a value of zero. Such a value indicates to the supervising device that the remote device has been reset. The supervising device or devices can respond to a reset condition as is appropriate for the system. 
   Subsequently, the remote devices, when functioning properly, periodically transmit first messages. Each such message has an identifier that incrementally increases or decreases in value. 
   Where the respective remote device has detected an event which requires that an event or second message be sent to a supervising device, the first such message can be sent from the respective remote device with the second message or event sequence identifier having a value of zero. Upon sending the event message to the supervising device, that value can be incremented or decremented. 
   When the next time period terminates for sending a first message to the supervisory device an included second message identifier will have an altered value. The supervising device, can respond to both the first sequence identifier as well as the second sequence identifier to determine that the remote unit is transmitting first sequence identifiers periodically as required. 
   The supervising device can also determine if an event has been missed. If an event has been missed, the supervisory device can provide appropriate warning indicia and can request additional transmissions from the remote device. 
     FIG. 1  illustrates a system  10  which embodies the invention. System  10  can incorporate one or more supervisory units, such as the exemplary supervisory unit  12 . The unit  12  can be implemented with or more programmable processors  12   a  and associated control software  12   b . Neither the characteristics of the processors nor the nature and type of the software  12   b  are limitations of the invention except as described in more detail below. It will also be understood that the system  10  could be implemented as a peer-to-peer system without departing from the spirit and scope of the present invention. 
   The system  10  can incorporate a plurality of remote devices of various types. For example, detectors of various conditions such as a plurality of detectors  16  in wireless communication with the supervisory unit  12  as well as pluralities of detectors of various types  18  which can communicate with the supervisory unit  12  via a wire medium  22 . 
   A plurality  24  of other types of devices, which could be output devices without limitation could be in communication with the supervisory system  12  via a wired medium  26 . It will also be understood that some of the members of the plurality  16  could also be output devices. 
   Detectors, members of pluralities  16  or  18  can include detectors of ambient conditions without limitation such as temperature, humidity, smoke, flame, position, velocity, infrared and the like all without limitation. Output devices, plurality  24 , can include without limitation solenoids, motors, audible or visual output devices and the like all without limitation. 
     FIG. 1A  illustrates an exemplary member  30  of the pluralities  16 ,  18 ,  24 . Those of skill will understand that a given device might include some or all of the indicated functionality. 
   Device  30  can include one or more sensors, inputs, or input devices,  32  and/or one or more outputs or output elements  34 . The sensors  32  and/or output elements  34  are coupled to control circuit  36 . The control circuit  36  can include at least one programmable processor  36   a  and control software  36   b.    
   The control circuits  36  are also coupled to wired/wireless input/output circuitry  38  for communicating via a wired or wireless medium  40  with supervisor units such as unit  12 , or, other devices. The device  30  can be carried by a housing  42 . 
     FIG. 2  is a flow diagram of exemplary processing which some or all of the members of the pluralities  16 ,  18  or  24  can carry out in accordance with the present invention. In the diagram of  FIG. 2 , the acronym ESID corresponds to a second message or event sequence identifier. The acronym PSID corresponds to a first message sequence identifier. 
   In the process  100  at  FIG. 2 , the respective member of the plurality  16 ,  18  or  24  is initially reset, step  102 . In this step values of the respective PSID and ESID can be set to zero. As described above, the respective devices transmit or emit them in event indicating messages (ESID) as well as periodic ping messages (ESID, PSID). 
   In a step  104  in the respective device makes a determination as to whether or not an event indicating message should be transmitted to either one or more of the supervisory devices, such as device  12 , or in a peer-to-peer type system to one or more other units. If so, in step  106  the appropriate message is transmitted along with the current value of ESID (transmitted as zero the first time). In a step  108  that value is incremented by one. 
   In a step  110  a determination has been made as to whether or not the ESID value has rolled over (for example values will roll over once they reach a value of 255 if 8 bit representations are used). If so, the ESID value is reset to a value of one in a step  112 . 
   Where an event message need not be sent, step  104 , a determination is made, step  116  as to whether the predetermined period has lapsed. If the time interval for sending the first message has lapsed, that message is transmitted or sent in step  118 . In this event, both the ping sequence identifier value and event message sequence identifier value are also transmitted to the supervisory device. 
   In a step  120  the first message sequence identifier is incremented. Where that value has rolled over and equals zero, step  122  it is reset to a value of one, step  124 . 
   Members of the pluralities  16 ,  18  and  24  continually repeat the process  100  in normal operation. If a given device fails, or, there is some disruption of the transmission medium, the supervisory device  12  will be able to determine one or more ping messages have not been received as illustrated by the processing  200  of  FIG. 3 . 
   The processing  200  of  FIG. 3  can be carried out at supervisory unit  12 . Alternately, in a peer-to-peer operating system that processing might be carried out in one or more of the distributed units all without limitation. 
   Where a supervisory device receives an event message, step  202  it evaluates the value of the second message or event sequence identifier, step  204 . If that value is zero, it is indicative of the fact that the respective device has been reset, step  206 . In this circumstance, the supervisory time out interval can be reset, step  208 . 
   Where a ping message has been received, step  210  and the associated PSID, first message sequence identifier has a value of zero, step  212  processing returns to step  206 . Alternately, in step  214 , the PSID value is incremented and checked for rollover, step  216 . If so, the PSID value is set to the numeric value of one, step  218  and process  200  executes step  220 . 
   In the event that the second message or event sequence identifier value is not equal to the prior ESID incremented by one, then the value is checked to determine if it equals zero, step  222 . If not, an event missed indicium can be produced, step  228 . That indicium can be transmitted to one or more of the members of the plurality  16 ,  18  or  24  as well as presented audibly or visually for an operator&#39;s response. Otherwise, in step  230  the current ESID value is evaluated, if it equals 1, the supervisory timeout is reset, step  208 , and the process  200  continues. 
   The above described processes  100 ,  200  are continually repeated by the respective members of the pluralities  16 ,  18 ,  24  or the supervisory system or systems  12 . It will be understood that the various steps of the processes  100 ,  200  and can be modified or added to without departing from the spirit and scope of the present invention. 
   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.