OPC UA Server Limitations

[justinL]

Hi,

Are there any known details for the limits on the amount of variables that can be used in a single instance of the process gateway running OPC UA server?

The context being, we're using Zenon to gather the process data from several different smart devices over MMS (IEC61850), then serving that collected data over OPC UA for a third party to connect to. Can 50,000 Zenon variables be broadcast over OPC UA without overwhelming the CPU on modern hardware?

Any insights on the resource limitations of the underlying Zenon OPC UA server implementation is much appreciated.

Thanks!
-Justin

[ursulak]

I've not tested OPC UA yet. But from test with another protocol i'm forecasting that not the summary quantity of variables will be important, just the rate of value changes (events to transfer per second).

The data transfer between zenon and (any) zenon Process Gateway goes via Windows COM interface (the same interface as API) from a single thread (common for all concurrent instances of zenPGs running on this particular PC). This single thread of zenon Service Engine (Runtime) occupies a single CPU core, thus when this core works constantly with load > 80% by max CPU frequency - you've got the problem. You can check the load of each CPU core in Task Manager - on tab 'performance' - 'change graph to' - 'logical processors'.

The max possible rate of events (value changes) per second depends on processor / Windows version, the quantity of online containers etc. I'm currently testing another zenPG on a PC with i9 processor and transferring 15k-20k [events/s] (on 100k variables). I suppose, in a project with 50 000 vars this would mean that in 1 second maximally <40% of those variables can change the value which be transferred to zenPG(s). Disclaimer: scenario not tested.

[justinL]

Appreciate the feedback