Yes, I thought about smoothing the rectified opto output to give a decent 24vdc at the plc input. I'm sure it would work.
In my application it is not too important if there is a little lag between the ac appearing and the 24dc plc input going true.
However it is really bad if the 24 vdc ' ac OK'signal persists much after the ac dissapears, hence too much capacitor would be a problem.
I think a better solution might be in holding the input DC when it rises to the 'on' level by means of a firmware timer which will hold over at least one cycle. The signal should go back to off one cycle or so after the ac fails.
Actually in this application it would be better if the ac OK signal dissapeared a little BEFORE the ac failed, but that would require a crystal ball instruction.
In my application it is not too important if there is a little lag between the ac appearing and the 24dc plc input going true.
However it is really bad if the 24 vdc ' ac OK'signal persists much after the ac dissapears, hence too much capacitor would be a problem.
I think a better solution might be in holding the input DC when it rises to the 'on' level by means of a firmware timer which will hold over at least one cycle. The signal should go back to off one cycle or so after the ac fails.
Actually in this application it would be better if the ac OK signal dissapeared a little BEFORE the ac failed, but that would require a crystal ball instruction.