GE GFK-0787B User Manual

tModular Redundancy Flexible Triple Modular Redundant (TMR) System 

In this very simple example, there are:
H a model 788 CPU (with 352 physical I/O).
H One output group of four discrete 16-circuit blocks. The application program will use

logical outputs at addresses %Q0001 to %Q0016.
h This requires just 16 output references, because the references used by all four blocks

in the group are the same. The references that these blocks will be configured to
respond to are assigned to the 16 bits at the end of the output table. Since the
example CPU is a model 788, the 16 references at the end are:

h The corresponding 16 bits in the Input Table are also reserved for GMR fault

detection disabling. The reserved input references are:

H One input group of three discrete 32-circuit blocks. The application program will use

voted inputs at addresses %I0001 to %I0032.
h The beginning Input Table reference for the data is equal to:

For the example, this is:

h In the output table, the corresponding area (%Q0913 to %Q1008) is reserved.

H One non-voted discrete 16-circuit block.

If configured as a combination block, it occupies references %I0033 to %I0048 in the Input
Table and %Q0033 to %Q0048 in the Output Table. Notice, as shown in the illustration,
that these references begin after the last voted input reference and that output references
%Q0017 to %Q0032 are not used.

The illustration shows where these inputs and outputs would be located in the I/O tables.
Shaded portions represent unused I/O table memory.

Voted  inputs = 32

bus A  inputs = 32

non-voted

 I/O =16

bus B  inputs = 32

bus C  inputs = 32

Reserved  inputs = 16

%I001 – %I0032

%I033 – %I0048

%I0913– %I0944

%I0945– %I0976

%I0977– %I1008

%I1009– %I1024

%Q0001 – %Q0016

%Q0033 – %Q0048

%Q0913 – %Q1008

%Q1009– %Q1024