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5
5-8 Genius Modular Redundancy Flexible Triple Modular Redundant (TMR) System
User’s Manual –March 1995
GFK-0787B
Operation of the Discrete Output Autotest
The PLC that is presently the autotest master informs the other PLCs (if any) which autotest
group it is about to test.
All PLCs read the diagnostic status of all blocks in the group to be tested, and will ignore any
subsequent faults that may occur in that group.
The autotest master PLC reads the current output state and force state for each circuit in the
output group.
Then, the autotest master pulse-tests the blocks in the output group (details of pulse test
operation are explained on page 5-10). The test sequence is described below.
1. For the 4-block output group, the autotest master overrides the normally
deenergized outputs on block C to ON.
Load
AB
C
D
Block C normally deenergized
outputs overridden ON
2. The autotest master pulse-tests block B. Any faults on block B are noted.
Load
AB
C
D
Block C outputs still
overridden ON
Block B Pulse-tested
3. If any outputs on block B configured as normally-energized logged a Failed Switch
when pulsed, the master overrides them to OFF.
Load
AB
C
D
Block C outputs still
overridden ON
Normally-energized
outputs with Failed Switch
are overridden OFF.