One-shot count is sporadic

[kaiser_will 65]

I am near completion of our first Allen-Bradley to Omron PLC program conversion and have one issue that is not working itself out yet. When a sequence of the machine runs, I have 4 different counters setup to increment once to keep track of number of cycles run. The issue is that all of the counters will sometimes count once per cycle, as they should, then other times make huge jumps. Omron tech support tells me that I should be able to change the trigger coil to Differentiate Up, but this feature is greyed out on all symbols. Omron is not aware of how to turn turn off the greyed out feature. How to unlock the greyed out features for coil edits? What elementary mistake am I making with my counters?

[scottmurphy 1]

Which model PLC are you using? If you can post a copy of your code, then we can take a look to see where you are going wrong.

[PMCR 66]

The differentiate up on the contact should not be greyed out for your PLC. The differentiate up option would be disabled on CPM1A, CPM2A, CQ.., C200H... PLCs, but I believe you are using a CJ1 PLC. Please provide a screen shot of the greyed out option so I can see it, along with the version of CX Programmer that you are using. The counter function is automatically a differentiated up function, meaning the count value will only decrement on the rising edge of the contact. Are you familiar with the data trace feature of the CJ PLC? It can be your best diagnostic tool for high speed troubleshooting such as this. I have posted a tutorial on the data trace feature if you are not familiar with it. http://forums.mrplc.com/index.php?autocom=downloads&showfile=663 I have an updated version for the data trace tool from CX Programmer V8, but it is not on this PC.

[kaiser_will 65]

The PLC model is a CS1G-CPU43H. Counters C49, C50, C51 are the problem children. We are an equipment OEM, typically integrating Allen-Bradley controls. This customer, however, requested Omron controls utilizing their "base" PLC and HMI programs. Thus, we have limited Omron programming history and have been hand-tied to use someone else's PLC program. I have found numerous errors in their base program, so I would not be surprised if that is the root of this issue. J5422_2008_10_20.cxp

[kaiser_will 65]

When I open the Edit features of the counter event trigger, 234.00, the Differentiate features are greyed out and Omron tech support is unaware of how to unlock these features.

[PMCR 66]

OK, you may have me stumped. I can edit the 234.00 for C50. What version of CX Programmer are you using? Now I see it. You have the dialog box open for a COIL, not a CONTACT. You cannot differentiate a COIL. For that, you would use a DIFU instruction. I don't know why the COIL dialog box is opened. I have never seen CX Programmer do anything like that. Edited 21 Oct 2008 by PMCR

[kaiser_will 65]

Allright guys, doughead me figured out that I was trying to change the COIL to differentiate up. Homer says "DOH". I made the change (thank you all very much) and it is working as expected.