Any idea why my counter won't count?

I just don't get it. I:1/6 when made should make the Accum of either C5:6 or C5:7 go up depending on if I:1/27 is made or not.
Here is what I do know, I:1/6 is changing state (it is a photoeye that I flag and when online with the PLC, I can see it change state, futhermore on the PLC itsself I see the LED light go on & off) as is the I:1/27 (which is a micro-switch).


Furthermore which is odd, is I made this progrom on a PLC in my office and tested it and it worked fine. What I don't get is why when implemented into the larger program, it doesn't work.
Any thoughts on this would be great. Thanks all.

Do you have a JSR in the main routine?

First thought: Is this a subroutine and is the subroutine actually being scanned? A non-scanned subroutine will still accurately show the state of all IO, but none of the instructions are actually running.

Check to see if something else is reseting your counter, maybe they are already being used in the program.

Alaric said:

First thought: Is this a subroutine and is the subroutine actually being scanned? A non-scanned subroutine will still accurately show the state of all IO, but none of the instructions are actually running.

Click to expand...

Yes this is. That is probably the problem. I've never really implemented a JSR. I actually haven't programmed that much, I had a class on PLCs about 5 years ago. All I normally do is change a timer, or troubleshoot I/O. I try sticking with running wires, test motors, etc. Unfortunalty I get stuck wit PLCs too. This site has been a big help.

You might try to enter a value in the Accumulator and see if it sticks or if it's being reset. You could also check for other Reset instructions (in RSLogix you can right click on the Reset instruction and do a Find All). For example.... if Rung 0006 true?
Also, if other rungs adjacent to this one are not toggling on and off you might have a subroutine or other control instruction issue.

DaleP said:

You might try to enter a value in the Accumulator and see if it sticks or if it's being reset. You could also check for other Reset instructions (in RSLogix you can right click on the Reset instruction and do a Find All). For example.... if Rung 0006 true?
Also, if other rungs adjacent to this one are not toggling on and off you might have a subroutine or other control instruction issue.

Click to expand...

That is just it, I did find all for everthing - counter, timer, Inputs, outputs. These are it.
I manually put in the full Accumm [12].
I even forced on the outputs, each one at a time since it a double acting solenoid.
All in all, nothing happend.
I am going to try an JSR

gappvembe said:

Yes this is. That is probably the problem. I've never really implemented a JSR. I actually haven't programmed that much, I had a class on PLCs about 5 years ago. All I normally do is change a timer, or troubleshoot I/O. I try sticking with running wires, test motors, etc. Unfortunalty I get stuck wit PLCs too. This site has been a big help.

Click to expand...

I'm assuming that you are using a SLC5/03 /04 or /05 since you are using 1746 IO cards. In the SLC platform routine 2 is your main routine. In routine 2 you need to insert an unconditional rung that has the JSR instruction on it and put this routine number in the JSR instruction. This will cause the program to jump over and process your new routine when the JSR is executed. After your new routine is done it will return to the calling JSR in the main program.

gappvembe said:

I even forced on the outputs, each one at a time since it a double acting solenoid.
All in all, nothing happend.

Click to expand...

With the ouputs forced on you still must enable forces before they will actually come on.

Alaric said:

I'm assuming that you are using a SLC5/03 /04 or /05 since you are using 1746 IO cards. In the SLC platform routine 2 is your main routine. In routine 2 you need to insert an unconditional rung that has the JSR instruction on it and put this routine number in the JSR instruction. This will cause the program to jump over and process your new routine when the JSR is executed. After your new routine is done it will return to the calling JSR in the main program.





With the ouputs forced on you still must enable forces before they will actually come on.

Click to expand...

Using the JSR worked!!!
Thanks all of you.
And yes I had to enable all forces for them to come on. Something I overlooked since normally anything I've come across already has that on.
Anyway as far as I can tell it will work like a charm. (The only reason it doesn't at the moment is I have to wait for a 24V Solenoid, since all we have here at the moment is 120V.