System OPC Write Value for version 8.1


I recently upgraded my Ignition edge from version 7.9 to 8.1 as I needed some driver modules from version 8.1.

I Imported the tags from my old version to new one and I could not find a way to replicate the “Write back to OPC item” feature from the old version.

Does anybody have an idea to how I could modify this for a quick deployment of the project.

It doesn’t exist. When importing a tag that uses that legacy feature, Ignition creates a tag value change event that replicates the functionality.

The legacy value change event seems not working. I’m getting an “Error in Configuration”

Is their any workaround to read from and write to OPC tag? thanks!

I think you have to touch up the values in the script. That script is the only way to do it.

Oh, wait! You said Edge ?

Edge won’t run tag events unless you have the Compute module. Talk to IA sales.

If you did a tag import into a fresh install, instead of upgrading or restoring a backup, that OPC UA server name might be incorrect. It’s “Ignition OPC UA Server” by default in 8.x, not “Ignition OPC-UA Server” (no hyphen).

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I removed the hyphen as you suggested.

I’m only getting a value in a particular expression tag but it doesn’t write the value onto another OPC tag.

I think Phil may be on to something with it requiring Edge Compute… this is ringing a bell but I can’t remember if there’s logic in Ignition to allow this particular script even without compute or if this turned out to be a corner case not supported on upgrade and the fix ended up being “complain to your sales rep” and see if you can get a free compute plugin on your license.

My Ignition Edge does have an Edge Compute plugin on Trial.

I’m not familiar with the script that I should be using.

Add some logging to the beginning of the legacy value change event to see that it is being run at all. Then you can narrow down your troubleshooting.

The one the import process wrote for you.

I think with Edge, some functionality doesn’t work even with a 2 hour trial. You may have to contact your account exec and get a 30 day trial.