What is "Device Properties/Tag Access Time Ms"?

On a Groov Rio device, MQTT Sparkplug channels have names like OptoMMP/Modules/Channels/PID_Temperature/Value

I could not understand what “OptoMMP” refers to, although it appears to be a choice that can be made on other Opto22 platforms. I see that other models have this “Device Type” decision between tag-based and OptoMMP-based methods.

On Groov Rio, is this an option? I couldn’t understand what the Device metric named “Tag Access Time Ms” means and would like to understand in what way this is a device property?

There are two data or tag sources on an EPIC, PAC Control tags and OptoMMP tags.
The PAC Control engine can expose (make public) given tags that the user may chose while they are programming the strategy.

RIO, since it does not have a PAC Control engine can only expose nominated OptoMMP tags.

If you would like to learn more about OptoMMP I can highly recommend reviewing the first chapter of the Protocol Guide: https://documents.opto22.com/1465_OptoMMP_Protocol_Guide.pdf

The “Tag Access Time Ms” is the scan time in milliseconds between the MQTT Data service software and the OptoMMP service software that is running on the RIO. The more OptoMMP tags (Or PAC Control tags on an EPIC) you make public, the longer this scan will take.

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Thanks. I wasn’t understanding what kind of tag this metric refers to, and now it makes sense there would be a few variables that do not apply in the context of a Rio.

Just to be clear, that metric very much applies. We generally don’t put fluff into a product.

I understand. I took this line of questioning to the Sparkplug specification Slack (Slack) because I see these two metrics “Tag Access Time Ms” and “Write Queue Depth” as not device properties but performance metrics. I’m trying to develop an automatic translation from Sparkplug into another data model, and these two metrics don’t fit the model. I think device properties should be constants, not variables.

As an outsider, I’d like to see these two metrics published with names Device Performance/Tag Access Time (note “Ms” is the unit, Sparkplug has a proper place for units to go") and Device Performance/Write Queue Depth. Thanks!