RSLogix 5000, Change tag values but not its state?

iadapt said:

I put the instruction on the Main Program routine just to eliminate the JSR issue to test the input.

Click to expand...

I'm tempted to ask, "But is your 'MainRoutine' actually the main routine, as configured in the Program (see below for the difference: the one with the underscore is the "real" mail, as indicated by the icon).

But the fact remains that you claim the value of the tag when monitored in the PLC is a "1", but the -| |- is not green.

Frankly, that's impossible. And it's independent of whether the ladder is being scanned.

The only way it can happen is if you have the wrong tag somewhere, and your HMI is linked to one tag, while another is linked to a similar tag. You could be offline with the program and a '1' will still change a contact green.

Click on the tag in the PLC logic. Right click and select Monitor "<tagname>".
What's the value?
Which instruction are you using: -| |- or -|/|- ?

Note that I'm leaving the HMI out of the equation. That's a red herring for now. I want to confirm that the value as monitored in the PLC is what should drive the output. The next step will be to see if you can change the value wholly using Logix. And that it if you do, it drives the output. THEN we'll bring the HMI back into things to see if it can change your bit.

One step at a time. This is how you troubleshoot.

I have seen an HMI change a bit you set but not change in the PLC because the communications between them is not actually working. The HMI only responds to the valve in it's database. If that database is not being updated with the actual PLC addresses then this can happen. Check the HMI log to see if it's actually communicating.

Aardwizz, yes the main routine is the MAIN routine. I am checking the HMI logs now.

Try posting some screen shots of your PLC and HMI logic if your still having trouble with this. Seeing the logic would provide alot more information than you could explain.

What is the Tag name you're trying to change. You aren't trying to write to an Digital Input are you? You're using a PLC Global Tag?

For example you didn't map your push button to Local:1:I.Data.0 are you?

Hello,

I solved the issue, I some how overlooked that the tag was in program not controller. So sorry for all the hard work you've all given. This was indeed a basic mistake I should have solved on my own. But I was working on the problem for a few minutes at a time and it never occurred to me until one of you mentioned it. Thank you all for your help.