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I/O Status Data
Fault Recovery
If a fault is detected, the safety output remains in the off state. The
procedure for activating the safety output data again is as follows.
1. Remove the cause of the error.
2. Turn off the safety output or outputs.
The safety output status turns on when the output-error latch
time has elapsed. The I/O indicator (red) turns off. The output
data can now be controlled.
In addition to I/O data, the module supports status data to check the
I/O circuits. The status data includes the following data, which can be
read by the PLC controllers.
Individual Point Input Status
(ON = Normal/OK, OFF = Fault/Alarm)
Combined Input Status
(ON = Normal/OK, OFF = Fault/Alarm)
Individual Point Output Status
(ON = Normal/OK, OFF = Fault/Alarm)
Combined Output Status
(ON = Normal/OK, OFF = Fault/Alarm)
Individual Output Readback
(actual ON/OFF state of the outputs)
Individual Test Output Status
(ON = Normal/OK, OFF = Fault/Alarm)
Normal flags indicate whether each safety input, safety output, or test
output is normal (normal status: ON, error (fault) status: OFF). For
fatal errors, communication connections may be broken, so the status
of the normal flags then cannot be read.
Combined flags are provided for an AND of the status of all safety
inputs or all safety outputs (when all inputs or outputs are normal:
ON, when one or more of them has an error: OFF). This is known as
the combined safety input/output status.
Output monitors indicate the actual ON/OFF status of each safety
output.
Understand the Operation of Safety Functions
Publication 1791DS-UM001H-EN-P - April 2009
29
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