MVP 2021 Ausman Posted April 18, 2015 MVP 2021 Report Share Posted April 18, 2015 Hi again all, I have been working on another brand of PLC lately and am now back to my Unitronics stuff. The other brand treats sequential "groups" of ladder work as part of the main scan. I spent hours yesterday trying to figure out why a linearisation wasn't working. I was developing the next stage of a program and just had one element in the ladder, to work from there. Double check everything and it should be working....hmmmm...why not? Maybe I've forgotten how to do the X/Y relationships. Change things around again, many many times and still no output to my MI. What is going on? Power is there and it all should be working. Finally in frustration I looked up other work and noted the subroutine calls. I hadn't put any into my ladder because of my using the other PLC type which didn't need them. I was simply doing the same thing, where I had a number of routines but had separated them into the general idea of what was happening in that part of the ladder. On the other PLC I didn't need to call them. In this case I was starting on all the linearisation that is going to happen, wth it all in its own subroutine. My big whinge is that Visilogic (9.7.0/0) shows the power rail as active across the ladder elements in a subroutine that isn't being called. This is what was constantly throwing me off. To my thinking this is a significant fault in the program. If I had seen that there wasn't any power I would have twigged immediately. But I was being told that it was there. I know that I should have realised my error, but it is easy to get confused when working with other PLCs, as one has to remember so many different ways of doing much the same thing. But having the power rail as showing didn't help at all!! And the other thing that really bugs me, which perhaps should be in a separate thread, is that you can't do even the most minor alterations to a program on line. This other brand lets it happen to a high stage of complexity. Whilst online you can enter an edit mode and use most of the elements available. It asks all the precautionary questions that one would expect when you tell it to commit, as I understand that in some instances such a capability has the possiblity of doing something catastrophic. However, used sensibly it is fantastic. It makes it so much easier to change your ladder when you have made a dumb error, or want to try another way. I wish Unitronics would try to find a way for this to happen......it is a right pain in the bum having to go through the entire download process if you just want to trial/change one tiny thing. cheers, Aus Quote Link to comment Share on other sites More sharing options...
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