Hi Experts
I am working on a project, which involves S7-1516 3PN/DP(has a limit of 20K tags) and Ignition 8.1, using OPC-UA having almost 19K tags. I am using optimised DBs & UDTs in TIA and UDTs as well in ignition perspective. The PLC scan time is around 200ms. Once a cmd is given from SCADA session, the plc action is instant but the scada take almost 5 to 30s to update the status. Any suggestions please that might help me minimizing this comms lag. Thanks
Show the device connection details page for the device connection in Ignition. Look to see if you have any overload % reported there. (Status > Connections > Devices -> Click the details button for the specific device)
Edit: missed that this is using OPC-UA and not siemens driver
Not applicable for OPC UA connections.
On a 1516? Thats a PLC with issues. Get a faster PLC or split it amongst more PLCs.
Apologies, the PLC has a scan cycle of 40ms.
This is clearly a hardware performance problem (the PLC, not Ignition). There are generally three approaches to address such problems:
OPC, by its very nature, puts most of the processing effort on the OPC server, as it must track and evaluate every sample for changes and determine what to queue versus what to report immediately.
Using a driver in Ignition simplifies the PLC work, while increasing the comms traffic, but all of the OPC processing is then done in Ignition. If the PLC and Ignition are local to each other, this is often a big performance win.
What are your tag group settings?
If you have enabled the web server on the CPU, you can check the live communication load which has helped me diagnose issues like this before.
@Kevin.Herron Below snippet for tag group settings. Every group has a rate of 1000ms or more and there is a difference of atleast 100ms or more in the rate between the tag groups.
Tag Groups used in UDTs
OPC UA settings in TIA
@pturmel Acknowledged, unfortunately cannot reduce the number of tags.
@dhiren.naidoo I will give it try, thanks
PLC Diag
I increased the CPU communication load %, which has improved communications slightly; however, we are still experiencing noticeable lag.
We are considering upgrading to Ignition v8.3 and switching to the Siemens Enhanced Driver, but we are not yet sure what would be involved in the upgrade process or whether it would resolve the issue.
Any recommendations on how we should proceed? Have anyone seen similar performance issues, and would upgrading to v8.3 with the Siemens Enhanced Driver be the best approach?
Thanks
Worth a try. It would take some of the workload off of the PLC. Otherwise, go back to my bullet list in comment #6.
There is no magic wand to fix PLC performance limitations.
