a little help with PLC programming

dana123 · May 11, 2006

Hello,
I was wondering if I could ask a question about programming....
I am VERY new to writing PLC but not troubleshooting. Anyway, I am trying to learn on a Micrologix 1000, using a PC and RSLogix 500.
I want to write a program to count up binary, on about 5 lights, using as an input a toggle switch.It should be a simple program, but I cannot get past a small problem. When I throw the switch, it keeps counting. I only want 1 pulse with the switch up, so it counts up slowly. I need to like de-bounce the switch, sort of. Any ideas???

Thanks,
Dana

bernie_carlton · May 12, 2006

Read up on and play with the instruction labled OSR.

bradal · May 12, 2006

You could use an upcounter instead of a timer, then it will only increment on each positive transistion. CTU instruction I do believe

dana123 · May 12, 2006

Thanks for the suggestions, I will look up both of those commands.

abwiz · May 12, 2006

Maybe if you share with us your current code, we can tell you what is wrong with it....

dana123 · May 15, 2006

my attempt

This is what I have so far. I used the CTU, because I could not
get the OSR to work.
It counts up to 8 but I cannot add any more sub rungs the way it is. Is there a limit on sub rungs?

Dana

tom_stalcup · May 15, 2006

I'm not sure what you mean by sub rungs....

tom_stalcup · May 15, 2006

Hmm... I think I just figured it out...
A-B does have a couple of quirks, and one of them is the way you branch around things in the code. Take a look at THIS post, specifically posts 4, 6, and 9. I think that'll answer your question about rungs.

If not, let me know, and we'll help you out some more.

dana123 · May 15, 2006

that works

Thanks Tom,
That works. There is probably a better way to do this,
but it works.

I never would have found that quirk out.
Thanks again.

Dana

tom_stalcup · May 15, 2006

Hehe... yes... It's definitely the "brute force" method.

Maybe for your next project you can come up with a "pattern" based method rather than a "memory" based method.

Good job with your first project! And welcome aboard......

panic mode · May 16, 2006

tom is right, but it's good to see that somone tries to do the job.

if you look closer at C5:0.ACC (hint switch to binary view) you will see that count is already stored in right format, you just have to pick bits you need...

dana123 · May 16, 2006

that's awesome!!!

Thats what I'm talking about....
I will try this, this evening. This looks WAY to easy.

This will really do the same thing????

Dana

a little help with PLC programming

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