Allen-Bradley GuardPLC 1753, Справочник по безопасности

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Publication 1753-RM002C-EN-P - September 2008 45
GuardPLC Controller and GuardPLC I/O Output Channels Chapter 4
Safety-related 2-pole
Digital Outputs
The information in this section applies to the 2-pole digital outputs of
the 1753-IB16XOB8 and 1753-IB8XOB8 modules.
Test Routines for 2-pole Digital Outputs
The modules are automatically tested during operation. These are the
essential test functions.
•
Read-back the output signal of the switching amplifier. The
switching threshold for a read back signal is 2V. Diodes are used
to prevent a feedback of signals.
•
Check the integrated (redundant) safety shutdown.
•
Perform a shutdown test of the outputs within the multiple fault
occurrence time for a max. of 200 µs. The minimum time
between two tests is 20 seconds.
•
Monitor line at 2-pole connection
– short-circuit to L+, L-
– short-circuit between 2-pole connections (1753-IB16XOB8
only)
– line break in one of the 2-pole lines (1753-IB16XOB8 only)
•
Test L- switch capability at 2-pole connection with line
monitoring (1753-IB16XOB8 only)
•
Monitor the output current of the device
The operating voltage of the entire system is monitored. All outputs
are de-energized at an undervoltage of < 13V.
1-pole / 2-pole Connection
The digital outputs can be configured as follows:
•
Digital output with 2-pole connection with line monitoring
•
Digital output with 2-pole connection without line monitoring
•
1-pole positive-switching digital output (DO+)
ATTENTION
Pulsed outputs must not be used as safety-related outputs (for
example, for the control of safety-related actuators) because
they are not safety rated.
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