Hello! I have a, admittedly very small, issue with Joulescope JS220: Whenever the power is removed (power cut, plug off), Joulescope starts with an initial state of powered off, meaning the test device connected between the Current +/- will not receive any power. The green LED is off. As soon as I start the Joulescope GUI power will be enabled and the device runs. It happens to me that sometimes the power is removed and I spend some time wondering and debugging my tested device, until I realize that it just doesn’t receive any power from Joulescope.
Is there any way we can have a setting for the initial power state, so I could change it to power on the test device when Joulescope is powered on?
Hi @Br101 - When the JS220 sensor-side is unpowered, Current + is disconnect from Current -. The JS220 does not have any persistent setting that can tell it to automatically power on the sensor. It waits to do anything until instructed by the host.
We do have an script dut_power.py which can ensure that all connected Joulescopes power up the sensor side and connect Current + to Current -. You use it like this:
python dut_power.py on
You could configure your computer to run this script at boot. However, this does solve the problem for unplugging and replugging Joulescopes. Is this enough to solve your problem?
If you also need to handle the JS220 unplug/replug case, then the script would need to remain running. On a hotplug JS220 insert event and when the Joulescope UI is not running, it would need to perform the same action. If you need this, I can modify this script to add a hotplug option. If you need this, let me know and let me know your host OS,
Hi thanks for the explanations and script. I was hoping there would be a persistent option (maybe you could add one in the future?) but this is not a very important issue. I just have to remember to look at the LED. Thanks
Hi @Br101 - The JS220 is specifically designed to not have persistent state, except for calibration. The JS220 architecture has no way to store this information easily on the controller side where it is needed, so it is likely not going to happen.
However, running a small python application on the host can have the same effect. If you change your mind and want help with this, please post here again!