Rockwell Automation AADvance Controller Safety Manual - Manual (Page 90)

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4-34 Document: 553630
ICSTT-RM446K-EN-P Issue: 10 _C
Safety Manual (AADvance Controller)
Input and Output Forcing
The AADvance AADvance Workbench supports forcing of individual inputs
and outputs. The AADvance Workbench uses the term 'locking' to describe
forcing.
It is important the implications of forcing (or locking) of input and
output points on the process and their impact on safety are understood by any
person using these facilities. It is the plant operators' responsibility to ensure
that if forced conditions are present that they do not jeopardize the functional
safety.
Forcing requires the program enable key to be fitted to the 9100 Processor
Base Unit and is intended only for the purposes of engineering, installation and
commissioning activities. When the system is in-service, maintenance overrides
for safety-related inputs and outputs should be implemented using the
application program instead.
The Force LED on the front of the T9110 Processor Module indicates when
one or more I/O points are forced. The application program can determine
how many points are currently forced; it is highly recommended that this
information be used to control an additional status display and/or for logging
purposes.
If the forcing facility is used when the system is in-service, a safety-
related input connected to an operator accessible switch shall be implemented
to initiate the removal of the force condition.
A list of the currently locked points is read back from the AADvance system
and made available within the AADvance Workbench.