JS220 jsdrv_open TimeoutError on Linux

Issues
1

HI

I am encountered a TimeoutError when trying to start my Joulescope JS220 UI on Ubuntu 24.04.4 LTS.

I have created a python virtual environment and i am working within the environment. Following are the command i have executed to start the Joulescope

source ~/venv/joulescope/bin/activate

python3 -m joulescope_ui

The UI is start up with out any issue. Following are the loge appeared on the screen

image
image537×468 7.4 KB

But While connecting JS220 to the system i am getting following error

The Error Log:

ERROR:2026-03-06 18:29:15,825:js220_updater.py:308:joulescope_ui.devices.jsdrv.device.u.&js220.000400:driver open failed
Traceback (most recent call last):
  File "/home/quest/venv/joulescope/lib/python3.12/site-packages/joulescope_ui/devices/jsdrv/js220_updater.py", line 306, in _run
    self._driver.open(self.device_path, mode='restore')
  File "pyjoulescope_driver/binding.pyx", line 995, in pyjoulescope_driver.binding.Driver.open
  File "pyjoulescope_driver/binding.pyx", line 726, in pyjoulescope_driver.binding._handle_rc
TimeoutError: jsdrv_open timed out | u/&js220/000400
WARNING:2026-03-06 18:29:15,827:js220_usb.c:391:jsdrv:ll_await timed out
ERROR:2026-03-06 18:29:15,839:js220_usb.c:604:jsdrv:OP_CONNECT timed out

Could you please suggest solution to come out of this error.

2

Hi @Ranjith and welcome to the Joulescope forum!

Your Joulescope is in the bootloader (&js220) trying to do a firmware update. Did you give udev permissions for the bootloader? See 72-joulescope.rules, which you may be able to use directly.

3

Hi @mliberty

Thank you for the reply.

I have only tried following steps

$ wget https://raw.githubusercontent.com/jetperch/joulescope_driver/main/99-joulescope.rules
$ sudo cp 99-joulescope.rules /etc/udev/rules.d/
$ sudo udevadm control --reload-rules

As you suggest i will try 72-joulescope.rules

Could you please let me know the steps to give udev permissions for the bootloader?

Also, Could you please let me know the steps for firmware update?

4

99-joulescope.rules uses an older syntax where you have to add your user to the plugdev group. 72-joulescope.rules uses the newer uaccess tag to grant permissions to all users.

The Joulescope UI will complete the firmware update automatically. You just need to start the UI and have it be able to open the instrument. Also, make sure that you plug your Joulescope directly into the host computer. No USB hubs, docks or adapters.