LabVIEW client receive ghost events when DS is stoped

I am observing a rather strange behavior.

My LV2020 on the Win 10 client subscribes to the data_change_event for sys/tg_test/1/ulong64_scalar. The timeout is set to 1 second. When Test Ds is running, everything works as expected. But when I stop the DS, at some point my client receives a ghost event with timeout = false.

How to reproduce this:

  • Configure a change_event for ulong64_scalar in JIVE, e.g. DeltaAbs = 1
  • Start the VI and observe the indicators.
  • Stop the test DS
  • Observe the indicators. After a few seconds, the timeout indicator shows false and the received value is set to zero

Can somebody explain this behavior?

Workaround is to check error code == 0 in the attribute raw data cluster.


Extra attachments:
https://tango-controls.org/media/pybb_upload/attachments/7199fc16-2295-4a5c-8fed-2514e862b150.vi