ni-gpib-usb-hs

A pure-Python, user-space driver for the National Instruments GPIB-USB-HS adapter itself — it works with any GPIB instrument at any address, not just one model. No NI-488.2. No linux-gpib. No kernel module. Just pyusb + libusb talking to the adapter directly.

from ni_gpib_usb_hs import NIUSBGPIB

with NIUSBGPIB() as gpib:
    print(gpib.query(22, "*IDN?"))    # or any instrument at any address

A ready-to-use wrapper for the Agilent/HP/Keysight 34401A multimeter ships alongside the driver as a worked example — swap in your own instrument's SCPI commands and it works the same way (see Quickstart):

from ni_gpib_usb_hs import Agilent34401A

with Agilent34401A(addr=22) as dmm:
    print(dmm.idn())            # HEWLETT-PACKARD,34401A,0,10-5-2
    print(dmm.voltage_dc())     # 0.0000334

Why this exists

The GPIB-USB-HS is a great, cheap way to get a modern host talking to old GPIB bench gear — except:

• NI ships no driver for Apple Silicon. NI-488.2/NI-VISA for macOS is Intel-only, and the kernel extension doesn't even load on macOS 13+.
• linux-gpib is the usual fallback on Linux/Raspberry Pi, but it can be a pain to build (out-of-tree kernel module, autotools, Python-binding install paths that vary by distro) — and on the hardware this was built against, a genuine, boxed NI GPIB-USB-HS reproducibly failed every addressed GPIB transfer under linux-gpib's ni_usb kernel driver (deterministic NIUSB_ADDRESSING_ERROR / USB -110 timeouts), even against git master and after ruling out cabling, the instrument, USB autosuspend, and every config knob.

The interesting part: the same adapter, driven directly over libusb with a from-scratch reimplementation of NI's wire protocol, worked immediately — clean register reads/writes, clean addressed transfers, real *IDN? and READ? replies from a 34401A. The fault was in the kernel driver's interrupt-endpoint handling on that particular host, not the hardware. This project is that reimplementation, cleaned up: synchronous bulk request/response only, no interrupt-endpoint monitoring, no kernel module — which means it also runs identically on macOS (incl. Apple Silicon) and Linux.

Install

# libusb (native library) — pyusb needs this
brew install libusb          # macOS
# sudo apt install libusb-1.0-0   # Debian/Ubuntu/Raspberry Pi OS

pip install ni-gpib-usb-hs

_{Want the latest unreleased code instead? Install from source — see Development below.}

Linux permissions

On Linux, plain USB device nodes are root-owned by default. Install the udev rule so your user can access the adapter without sudo:

sudo cp udev/99-ni-gpib-usb-hs.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules && sudo udevadm trigger
# log out/in (or add yourself to the "plugdev" group) for group membership to apply

macOS needs no special permissions.

Quickstart

python examples/idn.py 22          # *IDN? whatever is at GPIB address 22
python examples/measure_dc.py 22   # a few different ways to read DC volts

Talk to any GPIB instrument

NIUSBGPIB is a thin, general-purpose GPIB controller — it just addresses a device and moves bytes, so it works with anything on the bus (SCPI or not):

from ni_gpib_usb_hs import NIUSBGPIB

with NIUSBGPIB() as gpib:
    print(gpib.query(22, "*IDN?"))
    gpib.write(5, "OUTP ON")
    print(gpib.query(5, "MEAS:VOLT?"))

The bundled 34401A wrapper

Agilent34401A is a convenience wrapper around NIUSBGPIB for one specific instrument's command set (also works with HP 34401A / Keysight 34401A, which share it):

from ni_gpib_usb_hs import Agilent34401A

with Agilent34401A(addr=22) as dmm:
    # one-shot, autoranged
    print(dmm.voltage_dc())
    print(dmm.resistance_4wire())
    print(dmm.frequency())

    # fixed-range, low-noise, repeated reads (faster than MEASure? each time)
    dmm.configure_dc_volts(rng=10, nplc=10)
    for _ in range(5):
        print(dmm.read())
    print("mean of 10:", dmm.read_average(10))

    print(dmm.errors())   # drains SYSTem:ERRor? queue

Writing a wrapper for your own instrument

If you have a different instrument, ni_gpib_usb_hs/agilent34401a.py is a ~180-line template: a small class holding a GPIB address and an NIUSBGPIB, with methods that just call self.write(...)/self.query(...) with your instrument's SCPI commands. Or skip the wrapper entirely and use NIUSBGPIB directly, as above — plenty of use cases don't need one.

Hardware

• Tested against a genuine, Hungary-made NI GPIB-USB-HS (USB ID 3923:709b), talking to an HP/Agilent 34401A.
• Should work with any instrument on the bus, since the driver just implements the standard NI-USB wire protocol (register read/write, command, addressed write/read) — the 34401A wrapper is a convenience layer on top.
• Not tested against the GPIB-USB-HS+ (different USB PID) or the older GPIB-USB-B; PRs welcome if you have one.

How it works

The adapter exposes a Cypress FX2 USB front-end in front of an NI TNT4882 GPIB controller chip. NIUSBGPIB:

1. Performs the vendor control-transfer "ready" handshake (serial number + poll-ready).
2. Bulk-writes a 26-entry TNT4882 register init sequence (reset, handshake mode, T1 delay, interrupt-mask setup, controller address, system-controller bit).
3. Issues GPIB command bytes (UNL/talk-address/listen-address) over a bulk OUT/IN request-response pair to address instruments.
4. Issues write/read bulk transfers for the actual data, with EOI handling and NI's chunked read-response framing.

Every operation is a synchronous bulk OUT then bulk IN — there is no async interrupt-endpoint status monitoring, which keeps the implementation small and sidesteps whatever the kernel driver's interrupt path was tripping over.

See ni_gpib_usb_hs/controller.py for the full implementation (well-commented, ~300 lines).

Scope / limitations

• One controller, one instrument addressed at a time. No serial poll, no SRQ, no parallel poll.
• No secondary GPIB addressing.
• This is enough to drive the vast majority of SCPI bench instruments (anything you'd script with *IDN? / MEAS? / READ? style commands), but if you need interrupt-driven SRQ handling or multi-controller bus sharing, use linux-gpib or NI-488.2 instead.

Development

git clone https://github.com/embeddedci-com/ni-gpib-usb-hs
cd ni-gpib-usb-hs
python -m venv .venv && source .venv/bin/activate
pip install -e .
python examples/idn.py

Publishing (maintainers)

This repo publishes to PyPI via Trusted Publishing (OIDC) — no API tokens stored in CI. One-time setup, then every GitHub Release publishes automatically.

One-time setup:

1. Create the project on PyPI (either publish once manually, or use PyPI's "pending publisher" flow to register the name before any upload exists).
2. On PyPI → your project → Settings → Publishing, add a trusted publisher:
   • Owner: embeddedci-com (or your GitHub org/user)
   • Repository name: ni-gpib-usb-hs
   • Workflow name: publish.yml
   • Environment name: pypi
3. On GitHub → repo → Settings → Environments, create an environment named pypi (matches the workflow). Optionally add required reviewers for extra safety before a publish runs.

Every release:

1. Bump version in pyproject.toml and ni_gpib_usb_hs/__init__.py.
2. Commit, tag, and push:

   git commit -am "release: v0.1.0"
   git tag v0.1.0
   git push && git push --tags
   

3. On GitHub, Releases → Draft a new release, pick the tag, publish it. The Publish to PyPI workflow (.github/workflows/publish.yml) runs automatically and uploads the build to PyPI.

To test the packaging without publishing, run the build job locally:

python -m pip install build
python -m build          # produces dist/*.whl and dist/*.tar.gz

Or use workflow_dispatch to trigger publish.yml manually from the Actions tab if you ever need to re-run a publish.

Credits

The GPIB-USB-HS wire protocol implemented here (register layout, command framing, TNT4882 init sequence) is derived from the linux-gpib project's ni_usb kernel driver (drivers/gpib/ni_usb/ni_usb_gpib.c), © Frank Mori Hess and contributors, licensed GPL-2.0. This project is a from-scratch, user-space reimplementation of that protocol in Python — no code was copied — released under the same license (GPL-2.0-only) in respect of that heritage.

License

GPL-2.0-only. See LICENSE.