[COM] Communication issue with LeCroy WaveRunner oscilloscope using USB

[SengerM]

Instrument details

• Model: LeCroy WaveRunner 9254M
• Communication: USB
• Link to the documentation (if available): Link

Output of pyvisa-info

Machine Details:
   Platform ID:    Linux-5.11.0-43-generic-x86_64-with-glibc2.29
   Processor:      x86_64

Python:
   Implementation: CPython
   Executable:     /usr/bin/python3
   Version:        3.8.10
   Compiler:       GCC 9.3.0
   Bits:           64bit
   Build:          Nov 26 2021 20:14:08 (#default)
   Unicode:        UCS4

PyVISA Version: 1.11.3

Backends:
   ivi:
      Version: 1.11.3 (bundled with PyVISA)
      Binary library: Not found
   py:
      Version: 0.5.2
      ASRL INSTR:
         Please install PySerial (>=3.0) to use this resource type.
         No module named 'serial'
      USB INSTR: Available via PyUSB (1.2.1). Backend: libusb1
      USB RAW: Available via PyUSB (1.2.1). Backend: libusb1
      TCPIP INSTR: Available 
      TCPIP SOCKET: Available 
      GPIB INSTR:
         Please install linux-gpib (Linux) or gpib-ctypes (Windows, Linux) to use this resource type. Note that installing gpib-ctypes will give you access to a broader range of funcionality.
         No module named 'gpib

Description

I am getting usb.core.USBError: [Errno 32] Pipe error when I try to open the connection. This is my code:

import pyvisa

rm = pyvisa.ResourceManager()
print(rm.list_resources())

keithley = rm.open_resource('USB0::1510::9328::04481179::0::INSTR')
print(keithley.query('*IDN?'))

lecroy = rm.open_resource('USB0::1535::4131::4751N40408::0::INSTR')
print(lecroy.query('*IDN?'))

and the output

('USB0::1510::9328::04481179::0::INSTR', 'USB0::1535::4131::4751N40408::0::INSTR')
KEITHLEY INSTRUMENTS,MODEL 2470,04481179,1.6.8d

Traceback (most recent call last):
  File "deleteme.py", line 9, in <module>
    lecroy = rm.open_resource('USB0::1535::4131::4751N40408::0::INSTR')
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa/highlevel.py", line 3304, in open_resource
    res.open(access_mode, open_timeout)
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa/resources/resource.py", line 297, in open
    self.session, status = self._resource_manager.open_bare_resource(
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa/highlevel.py", line 3232, in open_bare_resource
    return self.visalib.open(self.session, resource_name, access_mode, open_timeout)
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa_py/highlevel.py", line 167, in open
    sess = cls(session, resource_name, parsed, open_timeout)
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa_py/sessions.py", line 323, in __init__
    self.after_parsing()
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa_py/usb.py", line 81, in after_parsing
    self.interface = self._intf_cls(
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa_py/protocols/usbtmc.py", line 305, in __init__
    self._enable_remote_control()
  File "/home/tct/.local/lib/python3.8/site-packages/pyvisa_py/protocols/usbtmc.py", line 311, in _enable_remote_control
    self.usb_dev.ctrl_transfer(
  File "/home/tct/.local/lib/python3.8/site-packages/usb/core.py", line 1082, in ctrl_transfer
    ret = self._ctx.backend.ctrl_transfer(
  File "/home/tct/.local/lib/python3.8/site-packages/usb/backend/libusb1.py", line 893, in ctrl_transfer
    ret = _check(self.lib.libusb_control_transfer(
  File "/home/tct/.local/lib/python3.8/site-packages/usb/backend/libusb1.py", line 604, in _check
    raise USBError(_strerror(ret), ret, _libusb_errno[ret])
usb.core.USBError: [Errno 32] Pipe error

As seen, the communication with the Keithley works fine but fails with the oscilloscope.

Let me add that I have communicated with this very same oscilloscope in the past from Windows using PyVISA (probably using the NI backend).

[SengerM]

Now it is working with the NI backend, but detail before it worked

I changed the oscilloscope to a different computer running Ubuntu 20.04 too, same configuration as the original. When I try to connect with the oscilloscope, the same error occurs. Now, with more time, I installed the NI-VISA library following the instructions for Ubuntu. So now in this computer pyvisa-info gives this:

/home/myself/local/lib/python3.8/site-packages/gpib_ctypes/gpib/gpib.py:54: UserWarning: GPIB library not found. Please manually load it using _load_lib(filename). All GPIB functions will raise OSError until the library is manually loaded.
  warnings.warn(message)
Machine Details:
   Platform ID:    Linux-5.4.0-91-generic-x86_64-with-glibc2.29
   Processor:      x86_64

Python:
   Implementation: CPython
   Executable:     /usr/bin/python3
   Version:        3.8.10
   Compiler:       GCC 9.3.0
   Bits:           64bit
   Build:          Nov 26 2021 20:14:08 (#default)
   Unicode:        UCS4

PyVISA Version: 1.11.3

Backends:
   ivi:
      Version: 1.11.3 (bundled with PyVISA)
      #1: /usr/lib/x86_64-linux-gnu/libvisa.so.21.0.0:
         found by: auto
         bitness: 64
         Vendor: National Instruments
         Impl. Version: National Instruments
         Spec. Version: National Instruments
   py:
      Version: 0.5.2
      ASRL INSTR: Available via PySerial (3.5)
      USB INSTR: Available via PyUSB (1.2.1). Backend: libusb1
      USB RAW: Available via PyUSB (1.2.1). Backend: libusb1
      TCPIP INSTR: Available 
      TCPIP SOCKET: Available 

After this, the following strange sequence of events happened:

1. I modified the first line of the script to use the NI backend: rm = pyvisa.ResourceManager('@ivi'). Then I run this script and obtained

Traceback (most recent call last):
  File "test_lecroy_the_new_one.py", line 10, in <module>
    osc = rm.open_resource('USB0::1535::4131::4751N40408::0::INSTR')
  File "/home/sengerm/.local/lib/python3.8/site-packages/pyvisa/highlevel.py", line 3304, in open_resource
    res.open(access_mode, open_timeout)
  File "/home/sengerm/.local/lib/python3.8/site-packages/pyvisa/resources/resource.py", line 297, in open
    self.session, status = self._resource_manager.open_bare_resource(
  File "/home/sengerm/.local/lib/python3.8/site-packages/pyvisa/highlevel.py", line 3232, in open_bare_resource
    return self.visalib.open(self.session, resource_name, access_mode, open_timeout)
  File "/home/sengerm/.local/lib/python3.8/site-packages/pyvisa/ctwrapper/functions.py", line 1851, in open
    ret = library.viOpen(
  File "/home/sengerm/.local/lib/python3.8/site-packages/pyvisa/ctwrapper/highlevel.py", line 222, in _return_handler
    return self.handle_return_value(session, ret_value)  # type: ignore
  File "/home/sengerm/.local/lib/python3.8/site-packages/pyvisa/highlevel.py", line 251, in handle_return_value
    raise errors.VisaIOError(rv)
pyvisa.errors.VisaIOError: VI_ERROR_RSRC_BUSY (-1073807246): The resource is valid, but VISA cannot currently access it.

Also noted that rm.list_resources() is now returning an empty tuple, i.e. is not seeing the oscilloscope.
2. Came back to rm = pyvisa.ResourceManager('@py'). As expected, the original error occurs.
3. Now the surprising part, just because I was bored in the lab I went back to rm = pyvisa.ResourceManager('@ivi') and now it is working without problems.

All this happened without restarting the computer or the oscilloscope in the middle. It just happened within 30 seconds or so I was doing this random tests.

I am just reporting this here in case it is of use to somebody, be it the developers (thank you BTW) or someone running into a similar issue (me in the future?).

[SengerM]

Just want to add a comment on this issue now that I have been dealing with it for a while. The problem persists, but there is a workaround. First of all, the switch between @py and @ivi that I described before still has to be done every now and then (not sure what triggers this). To forget about it now I am connecting to the oscilloscope in this way:

try:
	oscilloscope = pyvisa.ResourceManager('@ivi').open_resource(args.oscilloscope_visa_name)
except pyvisa.errors.VisaIOError:
	try:
		pyvisa.ResourceManager('@py').open_resource(args.oscilloscope_visa_name) # This I already know it won't work, but it triggers something that makes the `@ivi` to work.
	except:
		pass
	oscilloscope = pyvisa.ResourceManager('@ivi').open_resource(args.oscilloscope_visa_name) # Now this works. Don't ask me.

With this weird connection mechanism, it works most of the times. There is one more thing, and it is that sometimes the connection still fails due to a busy resource error or so (sorry I don't have it right now) and the solution to this is to go to the oscilloscope and navigate to Utilities → Utilities setup → Remote and here just click in Off and then back again to USBTMC. I have no idea if this fixes something within the oscilloscope or restarts some connection within Linux, but after this it works.

[mwcmwc12]

Just to chime in, we are seeing this error with 2 of our Lecroy scopes as well. It won't even open resource at all and faces the same pipe error.

Models are: Lecroy HDO6104 and Lecroy WaveRunning 8000HD

[MatthieuDartiailh]

Can you have a look at the discussion in #256 and see if any of the investigated solution works in your case ? The more feedback we get the better.