Controlling GPIB devices through USB port
This page includes information on how to communicate with GPIB devices using USB port from a linux PC.
Using Agilent 82357B USB-GPIB interface from Linux
82357B can be used from Linux using the linux-gpib driver. This section will explain how to install the driver and use it from python and other languages.
Installation
What you need
Linux kernel source (2.6.8 or above) python, python-dev fxload (from linux-hotplug project) lsusb (usbutils package)
Depending on your distribution, you may have to mount usbfs to /proc/bus/usb. (In Fedora, it is automatically mounted). If needed, you may want to add the following line to /etc/fstab
usbfs /proc/bus/usb usbfs defaults 0 0
Installing linux-gpib driver
Before installing linux-gpib driver, create a group gpib, by sudo vigr.
You want to add some users (e.g. controls) to gpib group so that those users can open GPIB devices.
Download the latest version from http://linux-gpib.sourceforge.net/
Expand the archive and execute the following,
./configure --enable-python-binding --with-linux-srcdir=/lib/modules/2.6.24-19/build
where 2.6.24-19 should be replaced by your kernel version.
make; sudo make install should install the driver.
Installing firmwares
Download the proprietary firmwares from http://linux-gpib.sourceforge.net/firmware/
Expand the archive and copy agilent_82357a/*.hex to /usr/share/usb/agilent_82357a/. If the target directory does not exist, make it.
Configuration file and scripts
Put the following file in /etc/. gpib.conf
Add the following lines to your /etc/modprobe.conf
alias char-major-160 gpib_common alias char-major-160-0 agilent_82357a alias gpib0 agilent_82357a
Put the following files into somewhere in your PATH.
Be sure to set the permission of those files to executable.
Change the group of /dev/gpib* to gpib and set the permission to group readable/writable.
chown root:gpib /dev/gpib*; chmod ug+rw /dev/gpib*
Usage
When you connect the GPIB-USB interface to your USB port, the kernel modules should be loaded automatically. If not, don't worry, the initGPIB script will load them.
First, execute initGPIB script. You have to have sudo privilege to run the script as a normal user. This script will load the kernel modules, load the firmware twice (a work around for the buggy firmware of 82357B) and execute gpib_config.
After initGPIB is completed, the "READY" LED on 82357B should be green.
Now connect 82357B to 4395A analyzer. On the 4395A keypad, go to [Local]->[SET ADDRESSES]->[ADDRESS:4395] and set it to 17. Also set [ADDRESS: CONTROLLER] to 0.
Do a measurement.
Run getgpibdata.py.
The command will output the data transfered from the analyzer into the standard output. So you can redirect it to a file like,
%getgpibdata.py > data.txt
Then data.txt will look like this,
+0.00000000000000E+000 +4.604457E-004 +6.25000000000000E+005 +3.845480E-005 +1.25000000000000E+006 +7.024327E-009 +1.87500000000000E+006 +1.066326E-009 +2.50000000000000E+006 +6.686992E-010 +3.12500000000000E+006 +2.618739E-010 ...
The first column is frequency, the second is, in this case, the magnitude of the CH1 spectrum. If you have CH2 active, you will have the third column. In the case of network analyzer mode, the second column is the real part of the transfer function and the third is the imaginary part.
How it works
GPIB devices are defined in /etc/gpib.conf. You have to specify the address of a device and assign an arbitrary name. The name is used later to search for a device in python scripts.
getgpibdata.py is a simple python script. You can modify it to communicate with any kind of GPIB devices.
Here is the programing manual for Agilent 4395A.
Alternative way (GPIB scripting in Python)
Software needed: