Python pyVISA GPIB connection issue - python

I'm trying to connect to a GPIB instrument using pyVISA but I get an error. I'm following the simple example on the pyVISA website: http://pyvisa.readthedocs.org/en/master/
I type the following code into the IPython console:
import visa
rm = visa.ResourceManager()
rm.list_resources()
Out[4]:
(u'USB0::0x0957::0x0D0B::MY49431510::INSTR',
u'USB0::0x0957::0x17BC::MY52400338::INSTR',
u'ASRL1::INSTR',
u'ASRL2::INSTR',
u'ASRL5::INSTR',
u'ASRL6::INSTR',
u'ASRL7::INSTR',
u'ASRL8::INSTR',
u'ASRL9::INSTR',
u'ASRL10::INSTR')
However, my GPIB instruments do not show up, just the serial ports and my USB instruments. When I launch the Agilent Connection Expert (or NI MAX) I can see all my GPIB instruments and can communicate with them. I also am able to communicate with the instruments without issue with Matlab.
So when I try and connect to the instrument with the line:
inst = rm.open_resource('GPIB0::19::INSTR')
It throws an error:
VisaIOError: VI_ERROR_INTF_NUM_NCONFIG (-1073807195): The interface type is valid but the specified interface number is not configured.
I've also tried to connect with the USB instruments that show up when I list the resources and they do not throw this error. However, when I try and do a simple query:
inst = rm.open_resource('USB0::0x0957::0x0D0B::MY49431510::INSTR')
inst.query("*IDN?")
Nothing gets returned and no errors get thrown.
I'm using Python(X,Y) 2.7.9.0 with Python version 2.7.9 32 bit
pyVISA version is 1.6.3
NI bitness is 32
Any guidance is appreciated as I'm new to Python.
Thanks


You probably need to start the resource manager with:
rm = ResourceManager('Path to library')
where Path to library is the location of the NI Vista Library.
Also try:
python -m visa info
to ensure that you have it installed with the same word length as the python version that you are running.


I was having the same issue, and did manage to fix it by setting the path address to: 'C:/Program Files/IVI Foundation/VISA/WinNT/agvisa/agbin/visa32.dll'. If you haven't found the solution, I hope it works for you as well.


I had exactly the same problem - USB resources showed up, GPIB resources didn't. I tried to open the resource exactly as you did, inst = rm.open_resource('GPIB0::22::INSTR') (with the GPIB address changed to that of one of my instruments) with exactly the same result. Some inspired random guessing led me to
inst = rm.open_resource('GPIB1::22::INSTR')
which worked perfectly! Once the instrument is open it shows up in the list of resources, as expected. I have no idea why the interface is seen as GPIB1.
I am using the Keysight/Agilent/HP IO libraries suite as my VISA library (the NI library is not installed), and an Agilent 82357B USB to GPIB interface. I did not have to do any customisation of my pyVisa installation to get this working. Which is nice.
Hope this helps!


I had the same problem (running 32-bit python 2.7 on a 64-bit win7), I got it fixed using
rm = ResourceManager('C:/Program Files (x86)/IVI Foundation/VISA/WinNT/agvisa/agbin/visa32.dll')
which is the 32-bit VISA path given in the "About Agilent IO Control" Information.


I have ni-visa and Agilent visa installed on my computer. However, pyvisa cannot access the Agilent 82357B device due to pointing to the wrong library.
I used this command to specify the right library, it worked for me. Couples of notes:
Find the right library for the device which is visa32.dll located in different installation directories depends on each visa packet.
Use forward slash for delimiting characters even it is on windows.
Specify visa packet in the command: rm = visa.ResourceManager('c:/....')


I had the same issue. The problem was that the automatically installed Windows driver was wrong and my device showed up as USB0::0x3923::0x702A::010A65AB::RAW in NI MAX.
It was solved by an update of the driver (device manager-> properties) from C:\Program Files\National Instruments\NI-488.2 (or where your driver is installed).
Now GPIB works also from python.


I observed same error report when running on a PC with visa library from Keysight. Replacing with visa dll from National Instruments solved the problem.

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I have a DeLorme Earthmate LT-40 USB GPS device that I used years ago with a Windows XP program. Out of curiosity I plugged it into my Raspberry Pi to see if I could read the data. I've managed to see data using sudo gpsmon at the command prompt so I would like to take this a step further and write a Python program to read the data. Not knowing very much about Python I've searched YouTube and google for possible solutions. It looks like that I need to import pynmea2. I used pip install pynmea2 to install the module. I keep getting
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MetaTrader5 libarary in Python 3.7

I am trying to analyze currency data using MT5 in Python but it is not working. I didn't understand where is the problem? even importing is not work
from MetaTrader5 import *
from datetime import date
# Initializing MT5 connection
MT5Initialize()
MT5WaitForTerminal()
print(MT5TerminalInfo())
print(MT5Version())
This is the error: MT5WaitForTerminal()RuntimeError: No IPC connection

I had the same issue and I found the following solution:
My terminal was downloaded from the broker site and probably had some modifications that block ipc connections.
I downloaded original software from https://www.metatrader5.com/en/download
and copied "Config" folder from broker's version.
Now python script works.

I have a computer with a Windows 10 64-bit installation where everything would work without a hitch. I also have another machine with a Windows 10 32-bit installation, which would always complain about an invalid IPC connection. Not the official MetaTrader 5 version, nor my broker's customized version would work out of the box.
I eventually fixed it by specifying the path to my broker's exe in the initialize function like below (check for your own path, and mind the use of / instead of \):
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PyVisa won't find my GIPB port

I tried downloading the PyVisa module with the NI Visa libraries to find the GPIB port and address of the Agilent E4350B but no matter what I try it won't find it. I have a short code:
import visa
rm = visa.ResourceManager()
print(rm.open_resource())
But all it prints out is
('ASRL1::INSTR', 'ASRL2::INSTR')
I try to just open it anyways with the address I have it set at:
rm.open_resource('GPIB0::5::INSTR')
But it gives me this:
pyvisa.errors.VisaIOError: VI_ERROR_LIBRARY_NFOUND (-1073807202): A code library required by VISA could not be located or loaded.
I am running the same bit versions of Python and PyVISA. Can anyone tell me why it's not finding it?

Pyusb on windows - no backend available

I'm trying to have my Python application interface with an NFC device via USB.
The best option seems to be PyUSB, but I can't get it to connect to the libusb backend.
I keep getting
ValueError: No backend available
I've looked at the stack trace, and found that usb/backend/libusb10.py (which is part of pyusb) is trying to load libusb-1.0.dll to use as the backend, but it can't find it. It's not that it's not in my path, it's not on my computer at all!
I have installed libusb-win32, but the resulting directory only seems to include libusb0.dll. Where is libusb-1.0.dll???!
I would love to know either where to get that dll, or even a different suggestion to get PyUSB to work on Windows 7.

Download and install libusb-win32-devel-filter-1.2.6.0.exe. It should work.

2021 and the problem still occurs on Windows (Windows 10). I solved it by installing pyusb and libusb and adding libusb path to Windows environment:
pip install pyusb
pip install libusb
libusb-1.0.dll will be automatically added to:
\venv\Lib\site-packages\libusb\_platform\_windows\x64
and
\venv\Lib\site-packages\libusb\_platform\_windows\x32
Now just add those paths (the full path) to Windows Path and restart CMD / PyCharm.

I had a similar issue recently trying to talk to a USB device I am developing. I scoured the web looking for libusb-1.0.dll's and had no luck. I found source code, but nothing built and ready to install. I ended up installing the libusb-win32 binaries, which is the libusb0.dll.
PyUSB will search for libusb-1.0, libusb0, and openUSB backends.
libusb0.dll was already on my system, but something was still not set up right, do PyUSB was not working.
I followed the directions here to download and install the driver using the GUI tools provided to install the filter driver, and the INF wizard. Note, it didn't work until I ran the INF wizard.
I'm pretty new to programming and I've found the lack of clear documentation/examples to string this all together rather frustrating.

I am using Python 2.6.5, libusb-win32-device.bin-0.1.12.1 and pyusb-1.0.0-a0 on a windows XP system and kept receiving ValueError: No backend available.
Since there wasn't any real help on the web for this problem I spent a lot of time finding that ctypes util.py uses the Path variable to find the library file. My path did not include windows\system32 and PYUSB didn't find the library. I updated the path variable and now the USB is working.

There's a simpler solution.
Download and unpack to C:\PATH the libusb-1.0.20 from download link
Then try this line:
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dev = usb.core.find(backend=backend, find_all=True)
Depending on your system, try either MS64 or MS32 version of the .dll
Update of 17/01/2020, after a request to share more code:
import usb.core
import usb.util
from infi.devicemanager import DeviceManager
dm = DeviceManager()
devices = dm.all_devices
for i in devices:
try:
print ('{} : address: {}, bus: {}, location: {}'.format(i.friendly_name, i.address, i.bus_number, i.location))
except Exception:
pass
import usb.backend.libusb1
backend = usb.backend.libusb1.get_backend(find_library=lambda x: "C:\\libusb-1.0.20\\MS32\\dll\\libusb-1.0.dll")
dev = usb.core.find(backend=backend, find_all=True)
def EnumerateUSB(): #I use a simple function that scans all known USB connections and saves their info in the file
with open("EnumerateUSBLog.txt", "w") as wf:
counter = 0
for d in dev:
try:
wf.write("USB Device number " + str(counter) + ":" + "\n")
wf.write(d._get_full_descriptor_str() + "\n")
wf.write(d.get_active_configuration() + "\n")
wf.write("\n")
counter += 1
except NotImplementedError:
wf.write("Device number " + str(counter) + "is busy." + "\n")
wf.write("\n")
counter += 1
except usb.core.USBError:
wf.write("Device number " + str(counter) + " is either disconnected or not found." + "\n")
wf.write("\n")
counter += 1
wf.close()

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What did work, however, is the comment by #user1495323 : I copied libusb-1.0.dll from
C:\Users\username\AppData\Roaming\Python\Python27\site-packages\libusb\_platform\_windows\x64\
to C:\Windows\System32\

download the latest libusb
Download libusb
Copy MS32\dll\libusb-1.0.dll to C:\Windows\SysWOW64
Copy MS64\dll\libusb-1.0.dll to C:\Windows\System32
3.
pip install libusb
Copy MS32\dll\libusb-1.0.dll to C:\Python\Python37-32\Lib\site-packages\libusb_platform_windows\x86
Copy MS64\dll\libusb-1.0.dll to C:\Python\Python37-32\Lib\site-packages\libusb_platform_windows\x64
This method works for me.

Had some problems with backendnotavailable at 2022 when I install pyusb and libusb on my Windows x64.
I've found a way to solve it reading -> Github solve explaining
To solve, first you need copy path to libusb-1.0.dll (..\envs<your_env_name>\Lib\site-packages\libusb_platform_windows\x64) at system's PATH variable.
Secondly restart IDE.
Third try to get_backend use usb.backend:
import usb.core
from usb.backend import libusb1
# it should find libusb-1.0.dll at our path variable
back = libusb1.get_backend()
print(type(back)) # return: <class 'usb.backend.libusb1._LibUSB'>
dev = usb.core.find(backend=back)
print(type(dev)) # return: <class 'usb.core.Device'>
# flag 'find_all=True' would return generator
# reprecent connected usb devices
dev_list = usb.core.find(find_all=True, backend=back)
print(type(dev_list)) # return: <class 'generator'>
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EDIT
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Just in case:
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I had the same problem too.
Then, I tried ActivePython2.7.x.x
Link->http://www.activestate.com/activepython/downloads
Download the 2.7.x.x 32-bit version. The 64-bit version doesn't allow the installation of pyusb!
Then install pyusb and proceed.
Works fine.

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