Fault tolerant communication monitor for a master/slave system

• US 6,298,376 B1
• Filed: 03/07/1997
• Issued: 10/02/2001
• Est. Priority Date: 03/07/1997
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Culler, Mark, Kertesz, Veronica, Pedersen, Karl D., Rosner, Lisa E., Krisciunas, Joseph, Rajaiah, Karanam, Wolf, Jonathan A.
• Primary Examiner(s): Maung, Zarni
• Assistant Examiner(s): Cardone, Jason D.
• Application Number:
  US08/813,258
• Time in Patent Office: 1,670 Days
• Field of Search: 395/184.01, 709/208, 709/209, 709/224, 709/203, 709/207, 709/223, 709/227, 709/244, 370/216, 370/242
• US Class Current: 709/209
• CPC Class Codes: G06F 11/2005 using redundant communication controllers
• CPC Class Codes: H04L 12/40202 by using a plurality of master stations
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks

Abstract

A communication bus containing master and slave devices includes a monitor unit for fault tolerant communications. In the event the master is unable to communicate, the monitor automatically assumes the master communication role. When more than one monitor is connected within the communications network, the monitor with the lowest communications address assumes the master communications role. The master includes software implementation that allows an operator to obtain data from any of the slave devices via the monitor.

Claims

1. A communication system comprising:

a communication bus;

a plurality of power management devices connected with said bus, all of said devices communicating within said bus in a slave mode;

a master processor connected with said bus operating in a master mode wherein said devices communicate with said master processor upon command;

a first monitor processor connected with said bus, wherein, when said master processor is operational, said first monitor processor communicates within said bus in a purely slave mode to obtain from any of said plurality of power management devices upon operator request, said first monitor processor periodically monitoring said bus for detecting communications from said master processor and, wherein, when said master processor is not operational, said first monitor processor communicates with said bus in a master mode.

2. The communication system of claim 1 including a second monitor processor connected with said bus, said second monitor processor communicating within said bus in a slave mode to obtain data from any of said plurality of power management devices upon operator request when said master processor or said first monitor processor is operational, and said second monitor processor periodically monitoring said bus and communicating within said bus in a master mode when said master processor and said first monitor processor are not operational.

3. The communication system of claim 2 further including a third monitor processor connected with said communication bus, said third monitor processor connected with said bus in a slave mode to obtain data from any of said plurality of power management devices upon operator request when said master process or said first monitor processor or said second monitor processor is operational, said third monitor processor periodically monitoring said bus and operating in a master mode when said master processor, said first monitor processor and said second monitor processor are not operational.

4. The communication system of claim 3 wherein said first monitor processor is assigned a lower address within said bus than said second monitor processor and said second monitor processor is assigned a lower address within said bus than said third monitor processor.

5. The communication system of claim 1 wherein said communications bus comprises an RS-485 format.

6. The communications system of claim 1 wherein said power management devices are selected from the group consisting of meters, circuits breakers and relays.

7. A method of providing fault tolerant communication within a communication bus comprising the steps of:

connecting a master processor within said communications bus for operating in a master mode;

connecting a plurality of power management devices within said communications bus for operating in a slave mode; and

connecting a first monitor processor within said communications bus;

setting said first monitor processor to slave mode;

using said first monitor processor to obtain data from any of said plurality of power management devices upon operator request;

initiating a timer for a preset period of time;

monitoring said bus with said first monitor processor during said preset period of time;

resetting said timer and repeating the step of monitoring said bus with said first monitor processor if communication from the master processor is detected on said bus;

setting said first monitor processor to master mode if communication from the master processor is not detected on said bus within said preset period of time.

8. The method of claim 7 including the step of connecting a second monitor processor within said communications bus for operating in a slave mode to obtain data from any of said plurality of power management devices upon operator request when said master processor or said first monitor processor is operational, and said second monitor processor periodically monitoring said bus and communicating within said bus in a master mode when said master processor and said first monitor processor are not operational.

9. The method of claim 8 including the step of connecting a third monitor processor from said communications for operating in a slave mode to obtain data from any of said plurality of power management devices upon operator request when said master processor or said first monitor processor or said second monitor processor is operational, said third monitor processor periodically monitoring said bus and operating in a master mode when said master processor, said first monitor processor and said second monitor processor are not operational.

10. The method of claim 9 including the step of assigning said first monitor processor a lower address than said second and third monitor processors.

11. The method of claim 9 including the step of assigning said second monitor processor a lower address than said third monitor processor.

12. The method of claim 7 including the step of configuring said communications bus for operating in an RS-485 format.