Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
1998-12-11
2001-06-26
Pope, Daryl (Department: 2736)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S502000, C340S504000, C340S508000, C340S533000, C340S539230
Reexamination Certificate
active
06252501
ABSTRACT:
FIELD OF THE INVENTION
The invention pertains to apparatus and methods for communicating signals between processors in multi-processor systems. More particularly, the invention pertains to such systems wherein the processors communicate with one another via a communications medium.
BACKGROUND OF THE INVENTION
Communications circuitry for use in multi-processor systems dedicated to monitoring or supervising regions is known. One example is disclosed in Tice et al U.S. Pat. No. 4,916,432 entitled Smoke and Fire Detection System Communication. Another is disclosed in Tice U.S. Pat. No. 5,525,962 entitled Communication System and Method. Both of the noted patents are assigned to the assignee hereof and are hereby incorporated herein by reference.
Another system is disclosed in copending application Ser. No. 08/906,277, filed Aug. 5, 1997 and entitled Multi-Processor Communication System. This application is also assigned to the assignee hereof and is also incorporated by reference.
While known systems are useful and have been effective, it would be desirable to be able to improve the level of reliability of transmission of information in a given system. Further, it would be desirable to be able to provide apparatus and methods of retransmission essentially automatically. Such an environment would be useful in supervision or alarm systems as well as in general purpose local area networks.
SUMMARY OF THE INVENTION
A multi-processor communications system or network provides for repeated transmissions of messages where an intended receiver signals that the received message failed an integrity test. In that event, those processors, not the intended recipients of the message, which had correctly received the message will automatically retransmit the message.
In one aspect, there can be a plurality of programmed processors which communicate by a bidirectional communications medium. The medium can correspond to the ambient atmosphere for RF, infrared or ultrasonic transmissions. Alternately, the medium can correspond to optical or wire cable for optical or electrical transmissions.
Each processor can analyze all received transmissions. Where a processor determines that it is not an intended recipient of a respective transmission, but where it has received that transmission with a predetermined degree of integrity, that processor, and any others so situated can “listen” for an “integrity deficient” message on the medium generated by the intended recipient of the message. In that instance, any processor which has properly received the message can rebroadcast same to the network. The rebroadcast message, coming from a different transmission source, may be received by the intended recipient with the required degree of integrity.
In another aspect, in a communication system, messages are transmitted to/from devices or to/from a control unit. In the event that errors are detected in the communications, the other devices in the system that did not detect any errors can act as repeaters of the original message. This will increase the likelihood of the message being received by all intended devices or the control unit without additional errors.
Marginal transmission lines or noise conditions in the system can be overcome because the devices that are acting as repeaters are likely to be closer to the devices or control unit having difficulty receiving the messages.
In another aspect, a system includes a plurality of communication units, wherein each of the units is in bidirectional communication with others of the units. The units include detection circuitry for receipt of messages transmitted by others of the units and transmission circuitry for broadcasting of messages to at least one other unit. The detection circuitry and the transmission circuitry are coupled to control circuitry.
A first transmitting unit sends a first message to a second unit. The second unit is required to send an acknowledgment message in response to receiving the message without error. At least a first, second, and third unit are capable of receiving the first message and storing it.
An acknowledgment message is not transmitted by the second unit in the presence of an error. The missing message thus indicates that there was a transmission error. In response to not receiving the acknowledgment message, at least a third unit retransmits the first message to the second unit.
If devices are operating as repeaters to pass messages between devices, the last unit that sent the message that was not received error free by the next unit is considered the first unit sending the first message. The next unit is considered the second unit.
In another system, a plurality of communication units is in bidirectional communication with others of the units. Each of the units includes detection circuitry for receipt of messages transmitted by at least one other unit and transmission circuitry for broadcasting of messages to at least one other unit. The detection circuitry and the transmission circuitry are coupled to control circuitry.
The system includes executable commands at the respective units to identify that a first transmitted message from a first unit was not received without error by a second unit. A third unit will repeat the first transmitted message when it has determined that the second unit did not receive the message without error.
A multi-processor communications system includes a plurality of processors that can communicate via a medium. At least a first programmed processor includes interface circuitry for transmitting a first file via the medium to a second processor. The system includes programs effective to identify that an error has occurred in transmitting the first file. In response, a third processor transmits a second file which contains at least part of the first file via the medium when an error has occurred in the first transmission.
The programs to identify that an error has occurred in transmission of the first file detect that the second processor did not send an acknowledgment message after the first processor transmitted the first message.
In yet another aspect, system operation can be verified by keeping track of the presence or absence of communication errors noted by respective devices of the system. For example, the devices which are monitoring the communications medium of the system can carry out an error or integrity check of each message being monitored, including those directed to other devices. Where errors have been detected, an internal flag can be set or indicator stored.
Subsequently, the respective device or devices can then transmit the error indicators in response to a message or command requesting a transmission of its error monitoring indicators. The command can be issued by another device or a common control element. Message integrity can be verified using check sums or any other suitable processes without departing from the spirit and scope of the present invention.
Advantageously, since all messages received by devices of the system will be assessed from the point of view of the integrity of the message, irrespective of whether that message is intended for the receiving device or not, the integrity of the communication medium can be evaluated. An inappropriately large incidence of transmission errors which are detected by a particular device may well be indicative of a need to carry out maintenance on the system in the vicinity of that device.
In a further aspect, each device of a multiple device system can function in a normal mode and a repeat mode. Each device can monitor the medium, whether wired or wireless. Data values received by multiple devices can be immediately retransmitted, via the medium,to increase received signal strength at the intended receiving device.
In this embodiment, all devices, except the intended receiving device retransmit, on a bit-by-bit basis information from an originating device. This retransmission occurs irrespective of the absence of errors in the received message. Hence, signal strength throughout the medium will be enhanced minimizing noise induced
Clow Robert J.
Howard Jerry L.
Keeler Manley S.
Tice Lee D.
Pittway Corporation
Pope Daryl
Rockey Milnamow & Katz Ltd.
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