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7
7-6 Genius Modular Redundancy Flexible Triple Modular Redundant (TMR) System
User’s Manual – March 1995
GFK-0787B
Discrete I/O Tables: Example
In this very simple example, there are:
a model 788 CPU (with 352 physical I/O).
One output group of four discrete 16-circuit blocks. The application program will use
logical outputs at addresses %Q0001 to %Q0016.
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:
%Q1009 to %Q1024
The corresponding 16 bits in the Input Table are also reserved for GMR fault
detection disabling. The reserved input references are:
%I1009 to %I1024
One input group of three discrete 32-circuit blocks. The application program will use
voted inputs at addresses %I0001 to %I0032.
The beginning Input Table reference for the data is equal to:
I/O Table length – reserved inputs – (3 X input data length for one group) +1
For the example, this is:
1024 – 16 – (3 x 32) +1 = 913 = %I0913
In the output table, the corresponding area (%Q0913 to %Q1008) is reserved.
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.
Discrete Input Table
Voted inputs = 32
bus A inputs = 32
non-voted
I/O =16
bus B inputs = 32
bus C inputs = 32
Reserved inputs = 16
Discrete Output Table
%Q1024
%Q1008
%Q0913
%I001 – %I0032
%I033 – %I0048
%I0913– %I0944
%I0945– %I0976
%I0977– %I1008
%I1009– %I1024
%Q0001 – %Q0016
%Q0033 – %Q0048
%Q0913 – %Q1008
%Q1009– %Q1024
%Q0001
%I0001
%I0913
%I1008
%I1024
%Q0033%I0033