exception propafgating to user

[michalelektryk]

As far as I understand the exceptions thrown by pyvisa-py should be caught by pyvisa and not propagate to user, yet when I'm trying to open device already opened in another process I get:
usb.core.USBError: [Errno 16] Resource busy

To Reproduce

Steps to reproduce the behavior:

1. connect to one device using pyvisa / pyvisa-py in the terminal
2. in another python instance run:

rm = pyvisa.ResourceManager('@py')
resources = rm.list_resources()
        for device in resources:
                device = self.rm.open_resource(device)
                response = device.query('*IDN?')

Full stacktrace

Traceback (most recent call last):
  File "/home/atomd/projekt_GUI/psu_talking/HW_manager.py", line 20, in __init__
    device = self.rm.open_resource(device)
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa/highlevel.py", line 3302, in open_resource
    res.open(access_mode, open_timeout)
    ~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa/resources/resource.py", line 290, in open
    self.session, status = self._resource_manager.open_bare_resource(
                           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        self._resource_name, access_mode, open_timeout
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa/highlevel.py", line 3227, in open_bare_resource
    return self.visalib.open(self.session, resource_name, access_mode, open_timeout)
           ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa_py/highlevel.py", line 196, in open
    sess = cls(session, resource_name, parsed, open_timeout)
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa_py/sessions.py", line 329, in __init__
    self.after_parsing()
    ~~~~~~~~~~~~~~~~~~^^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa_py/usb.py", line 99, in after_parsing
    self.interface = self._intf_cls(
                     ~~~~~~~~~~~~~~^
        int(self.parsed.manufacturer_id, 0),
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        int(self.parsed.model_code, 0),
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        self.parsed.serial_number,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa_py/protocols/usbtmc.py", line 315, in __init__
    self._capabilities = self._get_capabilities()
                         ~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/pyvisa_py/protocols/usbtmc.py", line 343, in _get_capabilities
    c = self.usb_dev.ctrl_transfer(
        usb.util.build_request_type(
    ...<8 lines>...
        timeout=self.timeout,
    )
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/usb/core.py", line 1091, in ctrl_transfer
    self._ctx.managed_claim_interface(self, interface_number)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/usb/core.py", line 113, in wrapper
    return f(self, *args, **kwargs)
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/usb/core.py", line 180, in managed_claim_interface
    self.backend.claim_interface(self.handle, i)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/usb/backend/libusb1.py", line 833, in claim_interface
    _check(self.lib.libusb_claim_interface(dev_handle.handle, intf))
    ~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/atomd/projekt_GUI/venv/lib/python3.14/site-packages/usb/backend/libusb1.py", line 604, in _check
    raise USBError(_strerror(ret), ret, _libusb_errno[ret])
usb.core.USBError: [Errno 16] Resource busy

[michalelektryk]

Actually it seems that talking to any usb device throws the error.