Kepware OPC Read Bits


I will be connecting to a Kepware OPC connection (IGS actually but they’re pretty much the same). I wanted to confirm if I could read a bit from an integer tag just by adding “.0” or “.1” to the end?

It seems like some OPC connections support this and some don’t. When I make an integer tag in the Programmable Device Simulator, it gives be an error if I add .0 or .1 at the end of the OPC path in the tag configuration in the designer.

I know that I could read the whole integer to a tag and then have an expression tag that uses getBit but I would prefer to just have one tag.


Whether this syntax is supported or not is entirely up to the server you’re connected to.

Even within our server, it depends on the driver whether that syntax has meaning or not, as you’ve discovered.

So, it sounds like there is something I can do on my end to make it work? Use a certain OPC driver? Do you know which one(s)?

Autosol Communication Manager supports this. You append {BA:1} for the 1st bit, {BA:2} for the 2nd bit, {BA:4} for the 3rd, etc in the OPCItemPath.

I cant speak for which of their drivers it supports, but I know for sure it works in controllogix.

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I don’t know which Kepware drivers support this.

If you were using our OPC server then I could tell you the Modbus and AB drivers generally do support the syntax.

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