awg-scpi

Description

Control of Arbitrary Waveform Generators (AWG) with SCPI Command Sets through python via PyVisa

This uses the brilliant PyVISA python package along with the PyVisa-PY access mode which eliminates the need for the (very buggy, in my experience) VISA library to be installed on your computer. However, PyVISA-PY does require libusb which is needed for FTDI control and other things.

The intent is to support as many AWGs as is possible. However, I only have access to one so that is what has been coded and tested. If you are interested in adding support for some other SCPI AWG, then contact me for details in how to add those.

Installation

The bible for installing Python packages is: https://packaging.python.org/en/latest/tutorials/installing-packages/ Ultimately, consult that page for how to install this package. If you prefer to try commands that worked when this package was written, go ahead and give the following a try.

To install the awg-scpi package, clone this GIT repository and then run the following command in the top level folder:

python -m pip install .

Alternatively, can add a path to this package to the environment variable PYTHONPATH or even add the path to it at the start of your python script. Use your favorite web search engine to find out more details. If you follow this route, you will need to also install all of the dependant packages which are shown below under Requirements.

Even better, awg-scpi is on PyPi. So you can simply use the following and the required dependancies should get installed for you:

pip install awg_scpi

Requirements

• argparse
• python
  • pyvisa no longer supports python 2.7+ so neither does this package
• pyvisa 1.11.3
• pyvisa-py 0.5.2
• quantiphy 2.3.0

With the use of pyvisa-py, you should not have to install the National Instruments VISA driver.

Features

This code is not an exhaustive coverage of all available commands and queries of AWGs. The features that do exist are mainly ones that improve productivity like saving and loading configuration.

Currently, this is a list of the features that are supported so far:

• needs to be updated

It is expected that new interfaces will be added over time to control and automate the AWG. The key features that would be good to add next are: ....

Channels

Almost all functions require a target channel. Once a channel is passed into a function, the object will remember it and make it the default for all subsequence function calls that do not supply a channel. The channel value is a string or can also be a list of strings, in the case of setupAutoscale(). Currently, the valid channel values are:

• '1' for analog channel 1
• '2' for analog channel 2

Usage and Examples

The code is a basic class for controlling and accessing the supported AWGs.

The examples are written to access the AWG over ethernet/TCPIP. So the examples need to know the IP address of your specific AWG. Also, PyVISA can support other access mechanisms, like USB. So the examples must be edited to use the resource string or VISA descriptor of your particular device. Alternatively, you can set an environment variable, AWG_IP to the desired VISA resource string before running the code. If not using ethernet to access your device, search online for the proper resource string needed to access your device.

For more detailed examples, see:

awg.py -h

A basic example that sets up a basic wave and enables the output.

from awg_scpi import AWG

from time import sleep    
import argparse
parser = argparse.ArgumentParser(description='Access and control an AWG')
parser.add_argument('chan', nargs='?', type=int, help='Channel to access/control (starts at 1)', default=1)
args = parser.parse_args()

from os import environ
resource = environ.get('AWG_IP', 'TCPIP0::172.16.2.13::INSTR')
instr = AWG(resource)

## Upgrade Object to best match based on IDN string
instr = instr.getBestClass()

## Open this object and work with it
instr.open()

print('Using SCPI Device:     ' + instr.idn() + ' of series: ' + instr.series + '\n')

# set the channel (can pass channel to each method or just set it
# once and it becomes the default for all following calls)
instr.channel = str(args.chan)

if instr.isOutputHiZ(instr.channel):
    print("Output High Impedance")
else:
    print("Output 50 ohm load")

instr.beeperOn()

# return to default parameters
instr.reset()               

instr.setWaveType('SINE')
instr.setFrequency(34.4590897823e3)
instr.setVoltageProtection(6.6)
instr.setAmplitude(3.2)
instr.setOffset(1.6)
instr.setPhase(0.45)

print("Voltage Protection is set to maximum: {}V Amplitude (assumes 0V offset)".format(instr.queryVoltageProtection()))

# turn on the channel
instr.outputOn()

# return to LOCAL mode
instr.setLocal()

instr.close()

Taking it Further

This implements a small subset of available commands.

For information on what is possible for the Siglent SDG6022X and other SDG series arbitrary waveform generators, see the SDG Series Arbitrary Waveform Generator

For what is possible with general instruments that adhere to the IEEE 488 SCPI specification, see the SCPI 1999 Specification and the SCPI Wikipedia entry.

Contact

Please send bug reports or feedback to Stephen Goadhouse