ControlLogix OPC Extended Parameters

Hello, does anyone know how to access ControlLogix “Extended Parameters” using an OPC tag?

This feature is available in FTView by using the “@” identifier (.@Description, .@EUMin, .@EUMax, etc)

Does the Ignition dev team have any plans to develop this?


It depends how FTView implements this, I guess.

It’s certainly not in any documentation I have access to.

It’s used as a suffix on any OPC tag as a “dot field” (but not visible in the OPC Tag Browser).

So your reference would be “[Device]TagInstance.@EUMin

It’s a HUGE advantage when it comes to data standardization.

Yeah, what I mean though, is that if this isn’t available via the CIP Read Tag service and is instead implemented by some proprietary or undocumented service, it’s unlikely we’ll be able to do it.

I’ll have to get a Wireshark capture of the traffic between FTView and a controller when I have some free time.

Okay, sounds good. It became available in FactoryTalk View 9.00 or later and 21.00 or higher Logix Controller.

Using “@Description” (string) is the easiest to test with.

Good luck!

According to the Knowledge Base:

“Because these tags are not exposed via the FactoryTalk Gateway or RSLinx Classic OPC servers, they cannot be accessed through any third party OPC client.”

I wouldn’t mind seeing what you come up with – might be worth adding to my Ethernet/IP module.

Has this become available since this post? (Aug 2019)
Sure would be nice to pull the tag description from ControlLogix…