Multiple HMIs

[BML59]

We have 5 displays that we want to turn on and off based off of conditions met in the ladder logic, however we are having trouble setting and resetting the displays in order to change them back and forth multiple times. We are using set and reset coils with positive transistors in a separate connected to the HMI bit.    

[Joe Tauser]

You are on the right track but it sounds like you are having trouble keeping your bits straight.  If you could upload your program we could have a look.

Joe T.

[Ausman]

10 hours ago, BML59 said:

We are using set and reset coils with positive transistors

I assume this was meant to be "transitions"!  Further to Joe's comment about keeping your bits straight, any use of a transitional contact to set and reset coils is a tenuous thing.  This is due to the fact that the transition occurs on only ONE scan.  If you have anything out of sequence in your ladder the transitions will not work like you expect.  It can be made to work, but may require lots of trouble shooting and rearranging elements as it is very easy to lose the plot of what is happening when doing something complex. Simply swapping one transition rung's position for another above or below it can often have profound changes.  As well, If something else goes astray with the ladder, your entire sequence of transitions might lose complete track of where they are up to. I always try to use other methods of screen control, that end up far easier to track what is going on, and also keep things on track.

cheers, Aus