What?

This is a set of Python classes for communicating with IEEE488/GPIB instruments which I use in my private lab.

The base class is "pylt" - PYthon LabTools - which defines the generic API that hides the particular details of getting HPIB working for this instrument.

As a result, a typical Python script for measuring something can look almost readable:

import u2004a

d = u2004a.u2004a()

# 1 MHz, -25 dBm, best resolution
d.config(1e6, -25, 4)

while True:
	print(d.measure())

Currently two hardware connections are supported: Prologix USB-GPIB adapter and direct USBTMC/USB488 connection.

Why?

For those of you who are happy with LabView, etc., this will look like yet another 1980s rerun. Now that I've said it, you don't need to waste email-bandwidth telling anybody that :-)

Yes, I am aware of py-visa and a few other efforts, but I needed something that worked and found that they generally spent a lot of code offering things I didn't need or even want.

Be aware that this is not even close to a nice and polished release, and that you will probably never see one either: This is a snapshot of what I happened to have on my lab-computer right now, and I will update it as time/need/inspiration strikes.

There is a sort of vision behind it which has matured as I went along and learned more and more Python, and I will try to move closer to that as I go. The best place to spot it is in the pylt.py file, where the methods all instruments should support are defaulted.

Prologix.biz USB-GPIB

The one thing you need to know is that you must tell where to find your instruments.

For instance:

    class hp3336c(prologix_usb.gpib_dev):
            def __init__(self, name = "gpib0", adr = 13):

"gpib0" corresponds to /dev/gpib0 (which is where one of my Prologix USB-GPIB adapters show up), and 13 is the bus address.

There is a nifty multiplexing facility built in, so you can talk to multiple instruments at a Prologix driven bus at the same time from the same Python script, without having to think about it.

USBTMC/USB488

This one caused me no end of pain. What a sucky standard, but at least it looks like the Agilent U2004A Power Sensor works reliably now.

You will need py-usb 1.0 and some backend for it; I use libusb.

Getting started

With git installed do:

cd /some/where
mkdir pylt
cd pylt
git clone git://github.com/bsdphk/pylt.git

Who?

Written by Poul-Henning Kamp, [email protected].

License?

/*

• ---

• "THE BEER-WARE LICENSE" (Revision 42):
• [email protected] wrote this file. As long as you retain this notice you
• can do whatever you want with this stuff. If we meet some day, and you think
• this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp

• ---

*/