dcps 0.5.4

Control of DC Power Supplies through python

dcps

Control of DC Power Supplies through python

This is intended to be a generic package to control various DC power supplies using various access methods with a common API. For now, this supports only the Rigol DP832A DC Power Supply, the Aim TTi PL-P Series of power supplies and the BK Precision 9115 DC power supply through pyVISA and the SCPI command set. For the RigolDP800 class, this should work with all Rigol DP8xx power supplies although it is only tested with the DP832A. Likewise, for the BK Precision supplies, several model numbers are similar to the 9115 and the command set is likely compatible.

As new power supplies are added, they should each have their own sub-package.

Installation

You need to install the pyvisa and pyvisa-py packages.

To install the dcps package, run the command:

python setup.py 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.

Even better, dcps is now on PyPi, so you can simply use the following and the required depedancies should get installed for you:

pip install dcps

Requirements

• python [Works with 2.7+ and 3+]
• pyvisa 1.9
  • avoid 1.11.0 because it fails to work on Fedora/CentOS/etc.
• pyvisa-py 0.2

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

If using the USB communications method, must also install:

• PyUSB 1.0.2
• libusb

WARNING!

Be really careful since you are controlling a power supply that may be connected to something that does not like to go to 33V when you meant 3.3V and it may express its displeasure by exploding all over the place. So be sure to do ALL testing without a device connected, as much as possible, and make use of the protections built into the power supply. For example, you can set voltage and current limits that the power supply will obey and ignore requests by these commands to go outside the allowable ranges. There are even SCPI commands to set these limits, but they are not in this class because I think it is safer that they be set manually. Of course, you can easily add those commands and do it programatically if you like living dangerously.

Usage

The code is a very basic class for controlling and accessing the supported power supplies. Before running any example, be extra sure that the power supply is disconnected from any device in case voltsges unexpectedly go to unexpected values.

If running the examples embedded in the individual package source files, be sure to edit the resource string or VISA descriptor of your particular device. For RigolDP800.py, you can also set an environment variable, DP800_IP to the desired resource string before running the code. For AimTTiPLP.py, there is a similar environment variable, TTIPLP_IP.

# Lookup environment variable DP800_IP and use it as the resource
# name or use the TCPIP0 string if the environment variable does
# not exist
from dcps import RigolDP800
from os import environ
resource = environ.get('DP800_IP', 'TCPIP0::172.16.2.13::INSTR')

# create your visa instrument
rigol = RigolDP800(resource)
rigol.open()

# set to channel 1
rigol.channel = 1

# Query the voltage/current limits of the power supply
print('Ch. {} Settings: {:6.4f} V  {:6.4f} A'.
         format(rigol.channel, rigol.queryVoltage(),
                    rigol.queryCurrent()))

# Enable output of channel
rigol.outputOn()

# Measure actual voltage and current
print('{:6.4f} V'.format(rigol.measureVoltage()))
print('{:6.4f} A'.format(rigol.measureCurrent()))

# change voltage output to 2.7V
rigol.setVoltage(2.7)

# turn off the channel
rigol.outputOff()

# return to LOCAL mode
rigol.setLocal()

rigol.close()

Taking it Further

This implements a small subset of available commands.

For information on what is possible for the Rigol DP8xx, see the Rigol DP800 Programming Guide

For information on what is possible for the Aim TTi PL-P power supplies, see the New PL & PL-P Series Instruction Manual

For information on what is possible for the BK Precision 9115 power supplies, see the Model: 9115 Multi-Range DC Power Supply PROGRAMMING MANUAL

For what is possible with general power supplies that adhere to the IEEE 488 SCPI specification, like the Rigol DP8xx, see the SCPI 1999 Specification and the SCPI Wikipedia entry.

Contact

Please send bug reports or feedback to Stephen Goadhouse