GE GFK-0787B user manual Input and Output Addressing for GMR, Discrete I/O Addressing

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Input and Output Addressing for GMR

I/O addressing for GMR is unlike a that of conventional Series 90-70 application. In a conventional application, input and output addresses are assigned sequentially, starting at the beginning of the Input Table and Output Table. In a GMR application, the GMR software automatically divides the Discrete Input and Output Tables and the Analog Input Table into special-purpose areas.

Discrete I/O Addressing

The discrete Input Table and Output Table are divided up into separate areas for redundant and non-voted data, as shown below.

Discrete Input Table %I0001

	Voted Inputs	Inputs to PLC
	Available for	non-voted
non-voted Inputs		I/O
	Bus A inputs	Bus A, B, C
	Bus B inputs	Inputs
	Bus C inputs
		Reserved
Reserved inputs

Discrete Output Table

Logical Redundant

Outputs

Available for

non-voted Outputs

Reserved memory

Physical Redundant

Outputs

%Q0001

Outputs from

PLC

non-voted

I/O

Reserved

Output

Memory

Reserved,

Outputs to

Blocks

%I1024 or %I12288

%Q1024 or %Q12288

H Voted inputs and logical redundant outputs occupy the beginning of the discrete I/O tables. Normally, the application program utilizes these inputs and outputs, although it can also access the rest of the I/O table data if necessary.

H Non-voted inputs and outputs occupy the next portions of the Input and Output Tables. These are the inputs and outputs of blocks that are present in the system either as non-voted blocks on GMR busses, or on other busses.

The starting address for non-voted data depends on the amount of redundant data, as explained above. In the same example, if there were 64 voted inputs and 48 logic outputs, non-voted I/O data would begin at addresses %I0065 and %Q049.

H The area of Output Table memory that corresponds to the bus A, B, and C input data in the Input Table is reserved. The reason this area is reserved is that input blocks used in redundancy are configured as combination input/output blocks. So the corresponding output references should not be used for other purposes.

H The last part of the Output Table is used for the copied physical redundant output data. This is the data that is actually sent to the Genius blocks that are included in the GMR configuration.

The same amount of memory is reserved in the corresponding area of the Input Table. It is used to allow GMR fault processing to be inhibited on a circuit-by-circuit basis for the corresponding physical redundant outputs.

H The total amount of I/O data available depends on the CPU type. For the model 788 CPU, there can be a total of 352 physical inputs and outputs or approximately 100 redundant I/Opoints.For the model 789, there can be a total of 12288 physical inputs and outputs (or a maximum of 4096 redundant I/O points).

GFK-0787B Chapter 7 Programming Information 7-5