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SCPI Instrument Toolkit

Python REPL for controlling lab instruments — oscilloscopes, power supplies, multimeters, and function generators — over VISA (USB, GPIB, Serial).

What can I do with this toolkit?

  • Drive a full bench from one prompt -- PSUs, DMMs, scopes, AWGs, SMUs, and the TI EV2300 USB-to-I2C adapter, all from the same REPL. See Supported Instruments.
  • Run measurement scripts -- for/while/if, variables, assert/check, parameter overrides, and a step debugger. See Scripting.
  • Practice without hardware -- 14 simulated instruments via --mock. See Mock Mode.
  • Log measurements and export to CSV -- assign-style measurement syntax, calc for derived values, log save to CSV. See Log & Calc.
  • Plot live or after the fact -- live plotting during sweeps, static plots from saved CSVs, ready for pandas/matplotlib analysis. See Plotting.
  • Reuse 15+ bundled examples -- PSU+DMM sweeps, scope captures, full lab-report workflows. See Examples.

Learning path

  1. Start with Mock Mode -- practice safely without hardware.
  2. Skim the Examples -- find the workflow closest to your lab.
  3. Read Scripting once you want to write your own tests.

Quick Start

1. Install

pip install git+https://github.com/T-O-M-Tool-Oauto-Mationator/scpi-instrument-toolkit.git

Requires NI-VISA for USB and GPIB instruments.

2. Launch

scpi-repl           # auto-discovers connected instruments
scpi-repl --mock    # simulate instruments (no hardware needed)

scpi-repl not recognized?

Run python -m lab_instruments once. On standard Windows the toolkit will automatically add the Scripts folder to your PATH — open a new terminal and scpi-repl will work.

On managed machines (TAMU VOAL and similar) where registry edits are blocked, use the module form as your permanent launch method: 

python -m lab_instruments
python -m lab_instruments --mock
See Troubleshooting for a session-only PATH fix and other tips.

One connection at a time

Instrument connections are exclusive. Only one program can hold the connection to a device at a time.

  • You cannot run the REPL and a Python script against the same instrument simultaneously.
  • You cannot have the REPL or a Python script connected while BQStudio (or any other vendor software) is open and using that instrument.

Close one program before opening the other. If you get a "resource busy" or "cannot open" error, check that no other terminal, script, or vendor tool is already connected.

3. Find your instruments

list          # show all connected instruments and their names
scan          # re-scan if you plugged something in after launch

Instruments are assigned names automatically based on type: psu1, psu2, dmm1, scope1, awg1, etc.

Listing Connected Instruments

4. Control an instrument

use psu1          # set psu1 as the active power supply
psu chan 1 on     # enable output
psu set 5.0 0.5   # set 5 V, 0.5 A current limit
psu meas v        # measure output voltage

5. Log results and export

The assignment syntax (label = instrument meas ...) saves a reading to the log with a label (name you choose). calc retrieves it by that label. log print shows the table. log save exports it.

output = psu meas v unit=V         # save voltage — label is "output"
dmm config vdc                     # set DMM to DC voltage mode
dmm_v = dmm meas unit=V            # save DMM reading — label is "dmm_v"
calc error dmm_v - output unit=V   # reference labels in math
log print                           # show the full results table
log save results.csv                # export to CSV

See Log & Calc for the full explanation of labels, calc, and export.

Addressing multiple instruments

When you have more than one instrument of the same type, they are numbered:

list
# → psu1: HP E3631A
# → psu2: Matrix MPS-6010H
# → scope1: Rigol DHO804

You can address them directly by prefixing any command:

psu1 set 5.0      # set psu1 without changing the active selection
psu2 set 12.0     # set psu2 at the same time

Or switch the active instrument with use:

use psu2
psu set 12.0      # now acts on psu2

Getting help

help              # list all commands
help psu          # inline help for a specific command
docs              # open this documentation in your browser
examples          # list bundled example scripts

What's in the docs

Page What it covers
Python API Control instruments from Python — autodiscovery, enums, direct instantiation
General Commands scan, force_scan, list, use, idn, raw, state, sleep, reload
PSU Power supply control and measurement
AWG Function generator — waveforms, frequency, amplitude
DMM Multimeter — measurement modes, logging
Scope Oscilloscope — channels, triggers, measurements, waveform capture
SMU Source measure unit — voltage/current sourcing and measurement
EV2300 USB-to-I2C adapter — SMBus register read/write, scan, probe
Scripting Scripts, variables, loops, directives — full reference
Examples Bundled example workflows with explanations
Log & Calc Measurement log, CSV export, derived calculations
Plotting Static plots, live plots, interactive charts, data selection, detail view
Instruments Supported models and connection setup
LabVIEW Bridge Calling instrument drivers from LabVIEW Python Nodes
Troubleshooting PATH issues, NI-VISA errors, managed machine workarounds