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OPC UA freezing problem

Timo

Hi,

Our plant has a Siemens S7-1500 with an OPC UA server. Citect Scada 8.1 (update 28) communicates with logic with the OPC UA client. If, for some reason, Citect cannot read the variables from the logic, the variables will be displayed in #BAD. After a while, all the variables whose value is constantly changing start to show the current value again. Variables with a static value (such as pump status) remain #BAD and do not recover until the Citect IO server is restarted. OPC UA client version is 4.01.04.000.

Is there any parameter to force the OPC UA client to read all variables?

I can't find in-depth information on Citect's OPC UA client, so any help is needed.

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  • Hi Timo,

    The OPCUA driver uses OPC UA Publish/Subscribe mechanism to get value updates. It does not use Read/Polling services to read all tag values. There is no parameter to enable reading all tags.

    The values will be displayed as #BAD if the driver loses the connection to the server. When the connection is re-established, the driver will recreate OPC UA items for all Citect tags (item monitoring mode set to “Disabled”) and will change the monitoring mode to “Monitoring” for tags which are subscribed in Citect.
    After that the server should send value updates for all subscribed tags. If it does not do it, it is likely a server issue.

    If there is some problem on the driver side, you will need to engage support. They would need the driver and wireshark logs at a minimum.

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  • Hi Timo,

    The OPCUA driver uses OPC UA Publish/Subscribe mechanism to get value updates. It does not use Read/Polling services to read all tag values. There is no parameter to enable reading all tags.

    The values will be displayed as #BAD if the driver loses the connection to the server. When the connection is re-established, the driver will recreate OPC UA items for all Citect tags (item monitoring mode set to “Disabled”) and will change the monitoring mode to “Monitoring” for tags which are subscribed in Citect.
    After that the server should send value updates for all subscribed tags. If it does not do it, it is likely a server issue.

    If there is some problem on the driver side, you will need to engage support. They would need the driver and wireshark logs at a minimum.

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