Dimitri Krut Posted August 22, 2018 Report Share Posted August 22, 2018 I am sure this topic has been addresses before, but I was not able to find references by searching and there were no similar examples/tutorials. Perhaps someone can point me to a prior discussion or an example. I need to control a geared AC motor for up and down motion of a small lift to two end point switches (top & bottom). If I use polarity reversing relays, I need to make sure that both up and down (HMI) buttons are not pressed at the same time. Questions: What's the best way to implement a tri state switch -- up, down and neutral or do a lockout of the unused button? Should I do polarity reversal in the PLC or wire up two double pole relays (the old fashioned way)? Thanks! Quote Link to comment Share on other sites More sharing options...
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