Article - CS294815
Expected behavior of _System._Error and _System._NoError Tags in Kepware Server
Modified: 09-Jun-2026
Applies To
- ThingWorx Kepware Server (legacy) 8.0 N/A to 6.18
- Kepware Server (formerly KEPServerEX) 5.21.236.0 to 7.1
Description
- How can I use the Device level system tag _System._Error or _System._NoError for monitoring device connectivity?
- What tag should I monitor for device alarms in Kepware?
- Is there a way to determine device connectivity?
- Customer use Channel.Device._System._Error tag to monitor connection to target OPC DA server and see inconsistent behavior with the tag
- The behaviour of the system tag Channel.Device._System._Error and Channel.Device._System._NoError in PTC Kepware Products
- Would like to confirm the expected behavior of the Kepware _System._NoError tag when it is referenced from ThingWorx
- Explain working of Channel.Device._System._Error and Channel.Device._System._NoError works in PTC Kepware Products
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