Rs500 sqo hold position after stop and restart

[Ken Moore]

The Rockwell step instructions have always been clunky. Nothing as straight forward as a drum. Anyway... with Rockwell software, I always just roll my own. Easier to read, easier to follow at 2am, and easy to modify.

 

[Aardwizz]

So if I am on step two and the timer has timed for 4 seconds when stop pushbutton is pressed once I hit restart it goes to the next step but the timer is still at the accumulated value of the last step so it will only time for whatever is left on the timer.i need it to stay in the position it was in at before the stand retain the value of timer after restart

Your MCR may be your problem.

Timers (TONs and RTOs) add to their .ACC each time they are scanned.

If you aren't scanning your RTO because the Stop jumps over the MCR, then when Start is applied the MCR is back on and the RTO will accumulate from the last time it was scanned, which could be minutes ago and thus set .DN, and advance the sequence because .ACC > 8 sec.

If your sequence is held and you aren't scanning the RTO, OTU the Timer .EN bit. Then when the RTO "wakes up", it will recognize a false-to-true transition of its .EN, and not count all the time it was asleep.

 

[drbitboy]

I think @Aarwizz nailed it.

The PLC cares not a whit what you want it to do, but it will mercilessly and inexorably do exactly what you tell it to do.

If you want a Stop press/Start press sequence to abort the current step and jump to the next step, then you need to tell the PLC to do just that.

Is this a homework assignment?


I had missed post #12. Can you post the assignment description? We won't supply code, but we can give hints.