GE GFK-0787B user manual Analog Input Voting

4

Analog 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 sets of data in areas A, B, and C of the analog Input Table. How it does the voting is described below. It places the resulting voted input value into the voted inputs area of the Input Table.

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

			Field Input Data			Single Input Provided
						to Application Logic
		Input 1		152
Field Input		Input 2		150			150
Data
		Input 3			110
	Duplex State				low, high,
					or average
	Default State				hold last,
					minimum, or
					maximum

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 that is used when there are two field inputs present. The Duplex State may be configured as the higher actual input value, the lower value, or an average of the two.

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.

The Default State can be configured as the last input state, or a specified maximum or minimum value.

GFK-0787B Chapter 4 PLC Subsystem 4-13