GE GFK-0787B user manual Overview

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Overview

The input subsystem is the part of a GMR system that gathers input data. It may consist of:

HGMR Input groups of 1 to 3 discrete or analog blocks

HIndividual non-voted discrete and analog blocks

The following illustration represents basic elements of an input subsystem.

Triple PLCs

		Triple Genius Busses
		Input Block Group
		Non-voted
		(non-redundant)
		Input Block
A	B	C
Triple Input Sensors

GMR blocks are arranged in ªgroupsº of 1, 2, or 3 blocks. Within a group, all the blocks must be the same type. The input group shown above consists of three Genius blocks. Each has its own input sensors monitoring the same parts of the application process. Each block sends the input data from its sensors to three Series 90-70 PLCs. For simplification, the illustration only shows one input circuit on each block. However, each group can serve multiple GMR inputs. In addition, circuits that are not needed for GMR inputs can be used for non-voted inputs or outputs.

Genius blocks broadcast their inputs. So each block's input data is received by all PLCs on the bus. The GMR system software in each PLC then performs input voting and provides the results to its application program. If all input data is not available, the software follows a configured voting adaptation scheme. Details of both discrete and analog input voting are in the PLC chapter.

In addition to the diagnostics capabilities of the Series 90-70 PLC and Genius I/O blocks, the GMR system provides autotesting and discrepancy reporting for GMR inputs.

Genius blocks configured for GMR operation automatically generate three copies of their standard Genius fault report messages. They send one copy to the PLC Bus Controller configured with serial bus address 31, one to 30, and one to 29. So all of the GMR PLCs are able to monitor the blocks for Genius diagnostics.

2-2	GeniustModular Redundancy Flexible Triple Modular Redundant (TMR) System	GFK-0787B
	User's Manual ± March 1995