SFC in CLX vs. PLC-5

I haven't done much with SFCs so I am trying to make sure all my bases are covered for a recent upgrade (and SFC conversion) I did from a PLC-5 to a CLX.

Each step had an action for running a ladder routine. The first rung of that routine had an OTE for a S10X_State bit to signify that state was active. It appears that in the PLC-5, this bit would go low when the step was not active, but there were no OTUs to unlatch it. In the CLX, I initially had the same setup, but once the step was done, that bit would remain high.

Is that one of the differences? What else should I be on the lookout for?

I would unlatch the bit right before the call, that way if the call turns it back on it will be on throughout the program, but off if not activated.

there were no OTUs to unlatch it.

In the CLX, I initially had the same setup, but once the step was done, that bit would remain high.

What else should I be on the lookout for?

Click to expand...

based on your questions, the screen shot below might be helpful - at least as a starting point for additional research ...

TIP: SFCs can be tricky when "unexpected" events take place ... depending on what type of equipment you're working on – you might want to give some serious thought about things like power failures – faults – operator errors – etc. ...

the main thing is to consider how – and where in the program steps – the processor should start back up again after something out of the ordinary has been corrected ... specifically, don't just assume that everything will just start back up again in what would be the initial "step" or "home/default" condition ...

good luck with your project ...
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