Measurements that disappear when the joulescope is disconnected

I use JS220 with Joulescope UI (1.0.31).
I take my measurements and press the pause button. But if I unplug the Joulescope, my measurements disappear (see picture below). This can be annoying when the Joulescope is accidentally unplugged.


Hi @nano1 and welcome to the Joulescope forum! Thank you for taking the time to provide feedback.

With the current implementation, the fact that the Waveform widget continues to display the summary waveform at the top after removal is inconsistent. To be consistent, the Waveform widget should also clear the summary waveform on Joulesocpe removal.

When a Joulescope is removed, all live-streaming data becomes stale. Displaying stale, old data that could be perceived as current data is very bad. We intentionally error on the side of only displaying the most recent data. At one time long ago, we accidentally persisted old data in the multimeter widget when the Joulescope was removed, and we received the exact opposite critique!

If you have already paused the live streaming sample data, I can see why you might want to preserve the memory buffer on device removal. This has some severe software implications as the software internals are advertising data from a device that is no longer present. While this could happen, it would be a fair amount of work.

If you really care about the data capture, I recommend recording to a file. No matter what happens, you can later load the file.

I have a few questions to better understand why this is occurring and help find an acceptable workaround:

  1. How often does this behavior occur that you accidentally unplug your Joulescope?
  2. Are you actually unplugging your Joulescope, or are you finding that plugging/unplugging other devices on USB is causing your Joulescope to disconnect? If so, can you provide more detail about your USB topology including the use of hubs, docks, & adapters?
  3. What type of environment are you working in where this seems to occur: your desk, while traveling, in a lab?
  4. Are you frequently unplugging other devices (like your device under test, debug adapters, etc)? Simply labeling the Joulescope USB connector may significantly help in this case.

See issue #226 on GitHub.