Reconnecting to Siemens OPC server takes a long time

We have an installation with a Siemens PLC, and use the internal OPC-UA server.

But every time we download an online change to the PLC, the OPC-UA server needs to restart, and we lose the connection between Ignition and the PLC for about 10 minutes.

There are around 22000 tags in our Ignition project, of which the majority is coming from that Siemens PLC. I hope that’s not too much, as Beckhoff is usually able to handle projects this size quite easily.

Does anyone know how to stop restarting the OPC-UA server when there’s no change to it, or how to speed up the reconnection time? 10 minutes is just too long.

Wow, that’s pretty bad. What’s the firmware revision? Do you have a ton of UDTs defined in the PLC?

Wow, indeed! Another tidbit for future anti-Siemens rants… /:

It’s version 2.6, the CPU is 1515F-2 PN.

We have 58 different UDTs, and about 200 instances of our main UDTs (motors, measurements, valves, …). I wouldn’t say that’s very much.

There seem to be a lot of loose tags.

What version of Ignition? Can you get a Wireshark capture started before doing an edit/save on the connection (assuming that also takes a long time)?

Later this morning I can dig around and see if there’s any loggers that might help as well. I’m just curious where the delay is - is it the process of creating a session and re-subscribing everything or is the server just not actually available for a while following a download?

My experience with the new OPC UA server in the S7-1200 is fairly similar, simple machine with a bit less then a 100 tags, took around a minute to reconnect the OPC UA server.

Upgrade the controller to v2.8 and TIA portal to v16.

The UA server won’t restart on normal code changes anymore and will warn you when it has to (like on DB changes downloads)

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I had heard this was coming, glad to see it landed.

The following also helps in speeding up recovery of the S7-1500 UA server after a restart:

  • Mark every tag and DB member as not accessible from HMI if you don’t need to read it externally (minor improvement)
  • Set your OB1 minimum scan somewhat longer than it typically takes. Evaluate the risk yourself. Major improvement in UA server start up
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Thanks for the help, we’ll try those, and see if it works.

To share our results:

  • upgrading the firmware did work in a sense that not every change now requires an OPC-UA restart
  • we were not able to significantly speed up the OPC-UA restart time.