EasyButton

You are trying to write directly to the outputs but when the ladder program is scanning (monitor mode), the ladder program is turning them back off. When you place the PLC in program mode, it stops scanning the ladder which prevents the program from changing the state of the outputs. Your next step is to dive into the ladder program and understand what it was designed to do. Then you can add to the program what is needed for integrating the OPC client to the program. It is not standard practice to leave a PLC in program mode and try to control it's outputs. HMIs are typically used to place the entire process into an "operating mode" allowing the ladder to perform the steps needed to complete the process. Example: "Fill tank push button" (OPC write) + "Tank not full" (Input) = "Tank fill valve" (Output). Did this system ever have a HMI on it before? If so, trying to mimic that is a great place to start. Bottom line, stop trying to write directly to the I/O.

Use Cross Reference Report to see what is used. I would try a low number, I am not familiar with the CQM but it looks like you need to stay away from D6000 and up. CrossRef.bmp CrossRef2.bmp

Should not matter but do you have Asynchronous Write available? Is there a ladder program in this PLC and is the output you are writing to in the program? Try writing to a DM that is not part of the program. I keep coming back to the idea that you write is happening but the ladder is overwriting...

What model PLC? What memory area are you trying to force or write to? Post some screen shots please

Did you try to write values directly from Kepware Quick Client to the PLC without your appication running? If this does not work, I suspect the problem is in the PLC. Maybe something in the ladder is writing over your change. Try using a bit that is not part of the program.

The hertz is equivalent to cycles per second.

Wondering how this one turned out?

Seems to have more to do with the load on the ETN card. With an NS on 9600 and Wonderware on 9601 the update time to Wonderware was greater than 5 seconds with no delay on the NS. Removed the NS and we were back to 1 second. Note the system is fitted with managed switches.

I would try an alternate connection for the NS screens. The polling rate is very fast with these, I think the slowest is 200ms and I have seen this cause issues with Wonderware DAS.

We got our hands on some square knockouts. Makes a nice hole but a bit of a pain

Many ways to skin a cat...(no cats were harmed in this post)

depending on your PLC, check out the instruction SUM, very clean.

Maybe not the best solution but here is what I would do: Link the data from the switched PLC to the one that stays on and have the NS poll all data from that PLC.

Seems to me that the reset will only execute if action is processed on the first scan?

Thanks Bob, but not exactly what Im looking for. The fiber controller link has been working great for us and we were in the process of installing CLK13s so we could build a redundant ring. A project was approved to use CJ2s not knowing that there is no such thing as a CJ1W-CLK13. I do not have any desire to make the switch to EIP. Well, I guess you can't have it all!