lambles
Member
Hi all,
This may or may not be a simple question. Another programmer has used a single OTE instruction on a rung with no other conditions to be permanently ON...internal bit, not real output to a card.
This bit is then monitored via message read from another PLC as a comms OK bit (irrelevant to this question)
I have twice deliberately caused a major fault to see what happens with this output. First occasion it stayed ON despite the ladder rails going from green to grey and obviously not scanning the file. The second time (same major fault) the output turn OFF, again ladder rails grey, not scanning.
Question....what would the expected behaviour be for this output when the processor faults (or even put to Program mode I suppose)
Stay ON? Turn OFF? Random/non-deterministic?
Thanks in advance. I can provide screenshots if necessary.
This may or may not be a simple question. Another programmer has used a single OTE instruction on a rung with no other conditions to be permanently ON...internal bit, not real output to a card.
This bit is then monitored via message read from another PLC as a comms OK bit (irrelevant to this question)
I have twice deliberately caused a major fault to see what happens with this output. First occasion it stayed ON despite the ladder rails going from green to grey and obviously not scanning the file. The second time (same major fault) the output turn OFF, again ladder rails grey, not scanning.
Question....what would the expected behaviour be for this output when the processor faults (or even put to Program mode I suppose)
Stay ON? Turn OFF? Random/non-deterministic?
Thanks in advance. I can provide screenshots if necessary.
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