Description

This is a python application for acquiring from the Keysight E4990A impedance analyzer. The script captures a frequency sweep from the E4990A and saves the data in a MAT file. The capture parameters are configured in the e4990a.ini file. The USB or ethernet interface of the E4990A can be used.

The PyVISA library is used to communicate with the device.

Execution

The application entry point is named e4990a.bat on Windows and e4990a on macOS / Linux. On macOS / Linux the permissions of the script need to be changed after extracting the zip archive:

$ chmod 755 e4990a

Run the application once to generate the default e4990a.ini. The INI file can then be edited or copied. Replace ./e4990a with e4990a.bat when running on Windows.

1. Set the capture parameters in e4990a.ini.

2. Execute the fixture compensation procedure.

    $ ./e4990a -c
    Opening resource: TCPIP::192.168.11.227::INSTR
    Starting fixture compensation procedure
    Put the test fixture's device contacts in the OPEN state and press [ENTER]
    Put the test fixture's device contacts in the SHORT state and press [ENTER]
   

3. Execute the script and accept the default filename for storing the data, or specify the filename. The .mat extension will be appended if not provided.

    $ ./e4990a
    Enter a filepath or press [ENTER] to accept the default (20181020T182322.mat):
   

The filename can be a relative or absolute path.

Instrument communication

USB and TCP/IP instrument communication is supported. The communication is configured in the [resource] section. Remove or comment-out the section for USB communication. For TCP/IP, set the ip_address.

The E4990A IP address can be discovered through the instrument panel System > Misc Setup > Network Setup > LAN Dialog. Manually assign a fixed IP address through the router to persist the configuration.

Options

View the configuration parameters:

$ ./e4990a -h

The configuration file can be specified using the --config parameter:

$ ./e4990a --config=e4990a-2.ini

Data files can be output to a specified directory using a specified prefix:

$ ./e4990a 20190705/DeviceA7

• The directory will be created if it does not exist.
• The forward slash must be used as the path separator, even on Windows.
• The extension .mat is appended if not specified.

A timestamp can be appended to the given filename using the -a parameter:

$ ./e4990a -a 20190705/DeviceA7
...
Data saved to "20190705\DeviceA7-20190705T213856.mat"

The default filename can be specified to avoid being prompted:

$ ./e4990a -d

The default filename is an ISO9601 datetime stamp.

INI File

Uniform sampling is supported with the following options:

start_frequency = 500e3
stop_frequency = 5e6
number_of_points = 401

Start and stop frequency are specified in Hz.

Segmented sampling is supported by specifying a single option:

segments = 500e3,1400e3,19,1410e3,2400e3,100,2500e3,5000e3,26

Each triplet specifies a single segment: start frequency, stop frequency, number of points (e.g. 500e3,1400e3,19). Any number of segments can be specified.

An error will occur if the options for both uniform and segmented sampling are specified in the INI file.

Reading Data

The MATLAB function read_e4990a_data.m reads the MAT file and returns a structure. The numeric fields of the structure, which are stored in the MAT file using their intrinsic types, are cast to type double for convenience of working with the data in MATLAB.

The MATLAB function plot_impedance.m plots the impedance data.

Development

1. (Windows only) Install Python to C:\Python39.
2. Clone this repository.
3. Run the install script (install.bat on Windows, install.sh on macOS).
4. Run the build_installer script (build_installer.bat on Windows, build_installer.sh on macOS).

After making code changes, run pylint and fix errors/warnings before commit:

$ pylint e4990a.py

The configuration of pylint is in .pylintrc.

Tested With

• Windows 10 and macOS 10.15
• Python 3.9.7 x86-64

Dependencies

• PyVISA-py
• PyVISA
• matplotlib
• scipy
• numpy
• Markdown
• pyinstaller

References

• Keysight E4990A impedance analyzer
• Keysight E4990A help