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5
5-11GFK-0787B Chapter 5 Diagnostics
GMR Discrepancy Reporting
The GMR software performs discrepancy reporting for:
Voted discrete inputs
Discrete outputs
Analog inputs
There is no discrepancy reporting for analog outputs.
Discrete Input Discrepancy Reporting
As explained in the chapter on PLC operation, the PLC compares corresponding inputs
from bus A, bus B, and bus C, and performs voting:
Field Input Data
Input A
Input B
Input C
0
0
1
PLC Performs
2 out of 3 Voting
0
Single Input Provided
to Application Logic
If there is a discrepancy between any original input data value for an input and its voted input
state, the PLC automatically places a message in the I/O Fault Table, where it is available to the
Logicmaster 90 software and the application program logic. Discrepancy faults are latched.
When a discrepancy occurs, the PLC sets the fault contact for that voted input. See page 5-25
for information about these fault contacts.
Discrepancy signals are filtered for the configured input discepancy filter time to eliminate
transient discrepancies caused by timing differences.
The following table shows possible discrepancies between the input data and voted input data.
Input Data
Voted
Discrepancy
A B C
Voted
Inputs
A B C
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
0
0
1
0
1
1
1
0
0
0
1
1
0
0
0
0
0
1
0
0
1
0
0
0
1
0
0
0
0
1
0