Allen-Bradley GuardPLC 1753, Safety Reference Manual

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Publication 1753-RM002C-EN-P - September 2008 49
GuardPLC Controller and GuardPLC I/O Output Channels Chapter 4
Analog Outputs in the
1753-IF8XOF4
The analog outputs are written once every cycle and the values are
saved internally.
All the outputs are non-safety related but they can all be shut down
safely.
To reach SIL 3, the outputs values must be read back via safety-related
analog inputs and evaluated in the application program. There are
also reactions to incorrect output values that must be specified.
Test Routines
Both the safety switches for the shutdown of all four outputs of the
module are automatically tested during operation.
Reaction to Error
If a faulty signal is detected, all contact outputs of the module are set
to the Safety (0) state via the safety switches in accordance with the
closed-circuit principle. This is also indicated by the FAULT diagnostic
LED indicator.
The error code signal enables you to provide additional fault handling
in the application program.
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