Hello all,
I was reading through the services that are provided by OPC UA. I was wondering if there is a way to implement filters on a monitoreditem, such as editing it from the tag group? If this is not possible I was wondering if it is on the horizon or there is a reason for not having it.
Thank you very much for your time
The OPC infrastructure in Ignition is really only exposed to drivers, and drivers have no access to tag groups or other tag properties. (Just pace and OPC Item Path.)
OPC Client connections abstract away the distinctions between internal OPC drivers and external OPC servers, as far as the tag subsystem is concerned.
Please share more about your needs/intentions.
My intention is to set a dead band filter for a 3rd party server so that not all tag changes are queued for sending to the client if it doesnt pass the dead band filter. My assumption is that the client would need to be able to set this dead band filter in some manner.
With the goal to limit unnecessary data traversing the network.
Yeah, not currently possible. But discussed. See this topic:
The target server would have to publish the nodes to implement the filter.
That's not quite how it works.
Deadband is one of the things you can configure for each Monitored Item when created: DataChangeFilter – OPC Unified Architecture – Part 4: Services
It's a contract between the OPC UA client and sever, not necessarily anything to do with devices.
We could expose this as a Tag Group property and have all Monitored Items for all tags in that group get created with the same deadband value. It's just not something we're doing, and it wouldn't effect the underlying sampling from that device in any way, just the traffic between client and server.
Is that service optional for servers? Not in an accusatory way, but I am wondering why isn't it implemented?
Doesn't matter. Ignition doesn't implement a method to get at it.
Historically, nobody knows enough about OPC UA to even know it's missing, and Ignition's outbound OPC UA client connections are not typically over links where bandwidth matters.
There's actually a lot of knobs you could turn, in theory, for OPC UA connections, subscriptions, monitored items, but that aren't exposed because nobody has really ever needed them, and most client-server connections happen over a fast local network.
Thank you everyone for the timely responses. Those are all of my questions answered