Average update time of the Connectivity Addon

Hey there!

Lately I’ve been working on different projects that involve PLC (connected via LAN cable with a Siemens S1500/TIA portal) testing and debugging with the help of the Connectivity addon. I was wondering what your experiences are with the average update time of the connected variables.

I’ve done a small scale test before, which gave me an average update time of just 20.0 ms. After this test, I did a big scale project/digital twin with lots of sensors (mostly Raycast sensors) and other variables, and these are the first results:

This is quite high, since we want to simulate encoders as well in the future. I made a script that changed all the RaycastSensor sample times from 0.01 to 0.04 s, and this were the new results:

Way better, still not fast enough. What are your experiences with making a OPC UA connection for PLC tests working with big layouts? Any tips on lowering the average update times?

Also, is this a problem on the hardware or software end? Is this solved by buying a fast desktop?

Thanks in advance for sharing your experiences!


Since almost all of the latency is under “plugin time”, the delays are likely outside VC software i.e. in the OPC UA server of the S1500.

I haven’t tested Siemens connectivity performance myself, but unless you are experiencing heavy CPU load on the machine that runs the OPC UA server (computer or a physical PLC?), buying a faster computer might not help.

Note that using “event-based” update mode on a variable group with direction simulation -> server can be very inefficient if your simulation variables change value at high frequency because that mode will do a separate write request for each value change to ensure all values are sent out.

In the direction server->simulation the event-based update mode works differently (it uses the OPC UA subsciption mechanism) and is usually much more efficient than cyclic.

You can use the free (just need to register to download) UaExpert software to performance test the Siemens OPC UA server.

Here is a quite extensive database of communication performance measurements for Siemens’ OPC UA server products.