GE GFK-0787B user manual Discrete Input Voting

4

Discrete Input Voting

Immediately after the input scan, before the application program execution begins, the GMR software performs input voting. It automatically reads and votes on the three (or two) sets of data in areas A, B, and C of the discrete Input Table.

If a failure (discrepancy fault, Autotest fault, or Genius fault) occurs, the GMR software adapts to reject the faulty data. Depending on the configuration of the input group, input voting may adapt from three inputs to two inputs to one input, or from three inputs to two inputs to the configured default state.

Field Input

Data

Input A

Input B

Input C

0

1

1

Single Input Provided to Application Logic

1

Duplex State

1

Default State

0

In addition to field input data, the GMR software may also make use of the input group's configured Duplex State and Default State in determining the final input value to provide to the PLC.

Duplex State The Duplex State is a ªtiebreakerº value used when there are two field inputs operating. Its operation is described on page 4-10.

Default State The Default State is the value that will be provided directly to the PLC instead of a voted input value if the following inputs fail:

HThe single input in a Simplex group.

HThe remaining input in a Duplex or Triplex group configured for 3±2±1±0 Voting Adaptation.

HEither of the two inputs to a Duplex group configured for 3±2±0 Voting Adaptation.

HEither of the two remaining inputs to a Triplex group configured for 3±2±0 Voting Adaptation.

4-8	GeniustModular Redundancy Flexible Triple Modular Redundant (TMR) System	GFK-0787B
	User's Manual ± March 1995