Omron C200HW-PRM21 Operation Manuals page 111

A.1. General guidelines on input data processing
The C200HW-PRM21 must be activated by setting the RUN bit (100.00) ON. It is recommended to always set
this bit ON whenever the PLC program runs. If the PLC is set to PROGRAM mode, or the program stops due
to a severe failure (FALS), this bit will turn OFF. If the unit detects this, it will Hold or Clear all slave output data,
depending on the setting of DM 1017 (default = Clear, i.e. remote outputs are turned OFF like local outputs).
Bit 102.00 indicates if the Master Unit transferred
input data from its buffer to the mapped input area in
the PLC memory. In case the PLC cycle time is
shorter than the bus cycle time this may not always
be the case. In case no new data is available,
processing of slave data may be skipped. If 102.00 is
OFF, the ladder program between the JMP
instruction and the corresponding JME instruction
will be skipped.
Before processing input data from a
PROFIBUS slave, it is recom-
mended to verify the corresponding
'slave active' bit. If the slave is not
exchanging data with the master,
the data in the allocated input area
may be invalid, and should not be
processed.
In this case, 200.02 is the slave
active bit of the slave with address
02, whose inputs are mapped to
IR350, and outputs to IR050.
This JME instruction signifies the end of the
PROFIBUS slave input data processing. The program
will continue here following the JMP command if no
new input data was available (if 102.00 was OFF).
If a slave active bit turns OFF during operation, this
signifies a communication breakdown or slave failure.
In this case, an alarm is triggered. Depending on the
severity of the failure, further emergency processing
may be added by the user.
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