How to Reference Boolean Array in KEPServer Equivalent

I’m using Ignition to get PLC tags through the GE Industrial Gateway OPC Server which is the equivalent of the KEPServer OPC UA server. The OPC server is configured with a tag that is a Boolean array. I’m trying to figure out how to configure an Ignition tag to reference a bit in that array. The KEPServer tag has a length of 256. If I configure my Ignition with an OPC Item Path of something like “channel.device.KepTag[60]” (like I do when referencing an array of floats) my tag quality goes to “Bad; unspecified”. If I append a 0 as the bit index to create an OPC Item Path of channel.device.KepTag[60].0 then the tag quality is good. Is that the required syntax for referencing a bit?

The syntax that constitutes a valid NodeId (OPC Item Path for an OPC tag from an OPC UA server) is entirely up to the OPC server. There is no client-side logic applied to OPC Item Paths that would isolate a bit inside a larger type for you.

I guess I didn’t word the question very well. I was hoping someone with experience using this OPC server could confirm that the syntax I’m using is required when using Ignition and this particular OPC server use case.

Thank you,


What I found is the address format channel.device.KepTag[X].Y is appropriate and I needed to treat the KEPServer tag as an array of 32-bit words. In order to reference the 61st element in the Boolean array I used a value of 1 for X and 28 for Y.