I want to read data from an Agilent 34401a DMM directly into python or matlab so the data can be automatically recorded. However, I can't seem to make the connection. On my computer the device is listed as an unknown device without drivers, matlab doesn't list it as available in the instrument control toolbox, and when I used pyvisa's resource manager to list connected devices, it came out blank. I've installed pyvisa to try to get python to work, and in matlab I have the instrument control tool box along with "Instrument Control Toolbox Support Package for Keysight (Agilent) IO Libraries and VISA Interface", "Instrument Control Toolbox Support Package for National Instruments VISA and ICP Interfaces", and "Agilent 34401A Digital Multimeter - Driver".

I'm not sure why the device won't recognize any drivers. Is there a step or software that is needed for these to run?

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    \$\begingroup\$ Have you looked for a driver on the manufacturer's website? If you can find it, install driver manually \$\endgroup\$ – AJN Dec 4 '20 at 18:20
  • \$\begingroup\$ Are you actually using GPIB? If so you need to start with the software support for whatever GPIB interface you have added to your PC. But if you're doing something else, like plugging a USB cord directly into the instrument, then you need to pursue that, presumably productline-unique driver or python userspace code and something like SCPI on top. SCPI is inspired by GPIB traditions, but transport-agnostic, while GPIB is mostly an electrical transport... \$\endgroup\$ – Chris Stratton Dec 4 '20 at 18:39
  • \$\begingroup\$ I just went through this with a Keysight setup. I had to install their IO Suite, and use their software to determined the Visa Address over USB. Once that was done, pyvisa was suddenly happy. Also, my USB interface on this fragile HP computer always requires a reboot after the USB device is plugged in. Good times. \$\endgroup\$ – Chris Knudsen Dec 4 '20 at 19:03
  • \$\begingroup\$ Let me know if you need more details... Use Keysight "Command Expert" to get the device's VISA address. \$\endgroup\$ – Chris Knudsen Dec 4 '20 at 19:05
  • \$\begingroup\$ Thank you Chris! Using Keysight "Command Expert" I was finally able to see the device, but when I try to connect to the device I get an error: Connection to IVI-COM_Ag34401A failed. IO error: HRESULT = 80040012. Do you have any idea how to fix that? It also still isn't showing up as an available resource using pyvisa and MATLAB doesn't see it in the toolbox either. \$\endgroup\$ – sqph Dec 8 '20 at 15:02

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