I’ve set up a virtual Siemens S7-1500SP PLC using Siemens PLCSIM Advanced. The built-in OPC UA server from PLCSIM Advanced is added to my Ignition Gateway as an OPC server, and the connection status in the Gateway shows Connected.
When I open the Ignition Gateway Quick Client, I can browse to a tag in the PLC (for example, a boolean tag), subscribe to it, and see the value update instantly when I change it in the PLC program.
However, in Ignition Designer, I can also browse to the same tag through the OPC Browser and add it to my Tag Browser. The tag shows a Good quality, but its value never changes, even though it updates correctly in the Quick Client.
This happens consistently — I’ve tested with different tag data types (boolean, integer, real) and the result is the same: Quick Client updates fine, Designer tag stays static.
What could cause a tag to show Good quality but not update in Designer, while it works perfectly in Quick Client? Could it be related to subscriptions, scan classes, or compatibility with PLCSIM Advanced’s OPC UA server?
If you can make the OPC UA connection without security and then get a Wireshark capture that includes browsing and adding the tags to the tag browser that would be useful. A screenshot of your Tag Group settings would be useful too if you’ve made any changes.
Can you leave the capture running and then toggle the boolean in the PLC program?
I don’t see anything wrong here. The server reports the initial value of false, and then the capture ends before further PublishResponse messages are received from the server.
Okay, I think the issue is that the clock on your Ignition Gateway is ~3 minutes ahead of the clock on the PLC server, and so Ignition’s tag system accepts the initial value but then ignores subsequent values because the timestamp associated with them, provided by the server, is in the past.
If it’s not that then I have no idea… the OPC UA subscription stuff is all working just fine.
edit:
Bleh, the timestamp thing doesn’t sound right. I'd only expect that behavior if new values arrived with timestamps older than the previous values, but that’s not what I see.
Support will have to help you with some loggers to trace this through the tag system and into the Designer if necessary. Make sure it’s not something silly like an expired trial.
Update – Issue Resolved
The problem was due to how I had defined my global DB. I had created a PLC UDT data type and referenced it in a predefined global DB, but its elements were not updating.
To fix this, I placed the previously defined PLC UDT elements directly into the DB inside a STRUCT data type. After making this change, the tags started updating correctly in the Designer.
