Is there a setting in the OPC/UA configuration that I can change to poll tags faster?

Ignition
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Hi Everyone,

Set Up
I am currently using ignition perspective 8.1.41 with a Siemens 1516 PLC. The PLC is connected to the ignition server via OPC/UA without the S7 driver. There are currently about 4000 tags of various data types. (bool, integer, real)

Problem
After about 3000 tags I started to get errors about too many monitored tags. The short-term solution was to split the tags into several different tag groups and then change between either polled or subscribed with different polling times (polled seemed to work better). After about 4000 tags the polling times have to be about 3-4 seconds which is too much for this process.

What I have tried
I have tried polling from the PLC with the same project from two different PCs. The result was that there was no change in the amount of tags that timed out. This leads me to believe that the limiting factor is not the PLC but instead the server.

I have also tried changing some of the OPC connection settings but I was not able to notice any change.

I tried monitoring the server resources and everything looked to be within a reasonable range.

Any help is appreciated,

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The Rate of the Tag Group your tags belong to controls this.

In Subscribed mode, which is preferred, we create Monitored Items on the server and tell the server the preferred Sampling Interval to use. There is no polling between OPC UA Client and Server in this mode - the Server polls the underlying data on its side, and reports changes to the Client.

In Read mode, the Ignition OPC UA Client issues Read requests for all the tags in that group, over and over, at the configured rate.

In either case, there's nothing else you can do on the Client side to make it faster. Request less tags, or some tags faster and some slower, or get more a performant S7 model in this case.

Pretty much never the case. It's always the PLC.

1 Like
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Or switch to a processor brand that has a dramatically more performant public native protocol, like Rockwell's ControlLogix/CompactLogix. :man_shrugging: