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UA Measurement system option?

07 Jan 2023 09:48 #11421 by support

OPC UA contains provisions for variables to declare their units of measurements, such as in: .
AFAIK there currently isn't a standardized way for the client to specify which units it wants (and enforce the conversions/unit switch).

What you are describing seems to be a vendor-specific to do that, so you won't find it in the OPC specs or QuickOPC documentation. But it appears to be done *through* OPC (as they say " writing to an OPC variable..."). So you just need to obtain the relevant information about it from the vendor, and then implement it in your code; the normal QuickOPC features should be sufficient to achieve it.


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06 Jan 2023 17:14 #11417 by janderscu
I am writing a fairly basic utility using the EasyOPC API to access a OPC UA server here on site to subscribe to a set of channels. All good with that. Now they have asked if I can add an option to my read utility to set an option on the controls server automatically when I connect to change a MeasurementSystem property that selects Metric, US, or Native value to toggle how the values are returned.

From the request:
"The measurement system used by your OPC client is, by default, the one set on the server side, which can be either US or METRIC, but we have the ability to change it when connecting, by writing to an OPC variable called MeasurementSystem the system to use as a text field (so literally US, METRIC or NATIVE, an empty field will use default and return what it is)."

So I've been searching for this option or something related to it in the EasyOPC documentation but cant find it. Can someone offer some insight?


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