====== Python IVI Readme ======

===== Introduction =====

Python IVI is a Python-based interpretation of the Interchangeable Virtual Instrument standard from the [[http://www.ivifoundation.org/|IVI foundation]].

===== Included drivers =====

  * Oscilloscopes (scope)
    * Agilent InfiniiVision 2000A/3000A series
    * Agilent InfiniiVision 6000A series
    * Agilent InfiniiVision 7000A/B series
    * Agilent Infiniium 90000A/90000X series
  * Function Generators (fgen)
    * Tektronix AWG2000 series
  * DC Power Supplies (dcpwr)
    * Agilent E3600A series
    * Agilent 603xA series
    * Rigol DP800 series
    * Rigol DP1000 series
    * Tektronix PS2520G/PS2521G
  * RF Power Meters (pwrmeter):
    * Agilent 436A
  * RF Signal Generators (rfsiggen)
    * Agilent 8642 A/B
  * Other
    * Agilent 8156A optical attenuator
    * Agilent 86140B series optical spectrum analyzer
    * Colby Instruments PDL10A Programmable Delay Line
    * DiCon Fiberoptics GP700 Programmable Fiberoptic Instrument
    * JDS Uniphase TB9 Series Optical Grating Filter
    * Tektronix AM5030 programmable current probe amplifier
    * Tektronix OA5000 series optical attenuator
===== Instrument communication =====

Python IVI can use Python VXI-11, Python USBTMC, pySerial and linux-gpib to connect to instruments.  The implementation of the initialize method takes a VISA resource string and attempts to connect to an instrument.  If the resource string starts with TCPIP, then Python IVI will attempt to use Python VXI-11.  If it starts with USB, it attempts to use Python USBTMC.  If it starts with GPIB, it will attempt to use linux-gpib's python interface.  If it starts with ASRL, it attemps to use pySerial.  Integration with PyVISA is planned, but not currently supported.  

===== A note on standards compliance =====

As the IVI standard only specifies the API for C, COM, and .NET, a Python implementation is inherently not compliant and hence this is not an implementation of the standard, but an interpretation that tries to remain as faithful as possibe while presenting a uniform, easy-to-use, sensible, python-style interface.

The Python IVI library is a Pythonized version of the .NET and COM IVI API specifications, with the CamelCase for everything but the class names replaced with lowercase_with_underscores.  The library most closely follows the .NET standard, with the calls that would require the .NET helper classes follwing the corresponding COM specifications.  There are some major deviations from the specification in order to be consistent with the spirit of the other IVI specifications.  The fgen class is the most obvious example of this, using properties instead of the getters and setters as required by the IVI specification.  


===== Requirements =====

  * Python 2 or Python 3
  * One or more communication extensions

===== Installation =====

Extract and run

<code>
# python setup.py install
</code>

==== Instrument Communication Extensions ====

Python IVI does not contain any IO drivers itself.  In order to communicate with an instrument, you must install one or more of the following drivers:

=== Python VXI11 ===

Python VXI11 provides a pure python TCP/IP driver for LAN based instruments that support the VXI11 protocol.  This includes most LXI instruments and also devices like the Agilent E2050 GPIB to LAN converter.  

Home page:
http://www.alexforencich.com/wiki/en/python-vxi11/start

GitHub repository:
https://github.com/alexforencich/python-vxi11

=== Python USBTMC ===

Python USBTMC provides a pure python USBTMC driver for instruments that support the USB Test and Measurement Class.  Python USBTMC uses PyUSB to connect to the instrument in a platform-independent manner.

Home page:
http://alexforencich.com/wiki/en/python-usbtmc/start

GitHub repository:
https://github.com/alexforencich/python-usbtmc

=== Linux GPIB ===

Python IVI provides an interface wrapper for the Linux GPIB driver.  If the Linux GPIB driver and its included Python interface available, Python IVI can use it to communicate with instruments via any GPIB interface supported by Linux GPIB.  

Home page:
http://linux-gpib.sourceforge.net/

=== pySerial ===

Python IVI provides an interface wrapper for the pySerial library.  If pySerial is installed, Python IVI can use it to communicate with instruments via the serial port.  

Home page:
http://pyserial.sourceforge.net/

===== Usage example =====

This sample Python code will use Python IVI connect to an Agilent MSO7104A over LXI (VXI-11), configure the timebase, trigger, and channel 1, capture a waveform, and read it out of the instrument.  

<code python>
# import Python IVI
import ivi
# connect to MSO7104A via LXI
mso = ivi.agilent.agilentMSO7104A("TCPIP0::192.168.1.104::INSTR")
# connect to MSO7104A via USBTMC
#mso = ivi.agilent.agilentMSO7104A("USB0::2391::5973::MY********::INSTR")
# configure timebase
mso.acquisition.time_per_record = 1e-3
# configure triggering
mso.trigger.type = 'edge'
mso.trigger.source = 'channel1'
mso.trigger.coupling = 'dc'
mso.trigger.edge.slope = 'positive'
mso.trigger.level = 0
# configure channel
mso.channels['channel1'].enabled = True
mso.channels['channel1'].offset = 0
mso.channels['channel1'].range = 4
mso.channels['channel1'].coupling = 'dc'
# initiate measurement
mso.measurement.initiate()
# read out channel 1 waveform data
waveform = mso.channels[0].measurement.fetch_waveform()
# measure peak-to-peak voltage
vpp = mso.channels[0].measurement.fetch_waveform_measurement("voltage_peak_to_peak")
# measure phase
phase = mso.channels['channel1'].measurement.fetch_waveform_measurement("phase", "channel2")
# save screenshot to file
png = mso.display.fetch_screenshot()
with open('screenshot.png', 'wb') as f:
    f.write(png)
# save setup to file
setup = mso.system.fetch_setup()
with open('setup.dat', 'wb') as f:
    f.write(setup)
# restore setup from file
with open('setup.dat', 'rb') as f:
    setup = f.read()
mso.system.load_setup(setup)
</code>

This sample Python code will use Python IVI to connect to a Tektronix AWG2021 through a GPIB to VXI11 bridge or serial (pySerial), generate a sinewave with numpy, and transfer it to channel 1.

<code python>
# import Python IVI
import ivi
# import numpy
from numpy import *
# connect to AWG2021 via GPIB
#awg = ivi.tektronix.tektronixAWG2021("GPIB0::25::INSTR")
# connect to AWG2021 via E2050A GPIB to VXI11 bridge
awg = ivi.tektronix.tektronixAWG2021("TCPIP0::192.168.1.105::gpib,25::INSTR")
# connect to AWG2021 via serial
#awg = ivi.tektronix.tektronixAWG2021("ASRL::/dev/ttyUSB0,9600::INSTR")
# create a waveform
n = 128
f = 1
a = 1
wfm = a*sin(2*pi/n*f*arange(0,n))
# transfer to AWG2021
awg.outputs[0].arbitrary.create_waveform(wfm)
# 2 volts peak to peak
awg.outputs[0].arbitrary.gain = 2.0
# zero offset
awg.outputs[0].arbitrary.gain = 0.0
# sample rate 128 MHz
arb.arbitrary.sample_rate = 128e6
# enable ouput
awg.outputs[0].enabled = True
</code>

This sample Python code will use Python IVI to connect to an Agilent E3649A and configure an output.

<code python>
# import Python IVI
import ivi
# connect to E3649A via GPIB
#psu = ivi.agilent.agilentE3649A("GPIB0::5::INSTR")
# connect to E3649A via E2050A GPIB to VXI11 bridge
psu = ivi.agilent.agilentE3649A("TCPIP0::192.168.1.105::gpib,5::INSTR")
# connect to E3649A via serial
#psu = ivi.agilent.agilentE3649A("ASRL::/dev/ttyUSB0,9600::INSTR")
# configure output
psu.outputs[0].configure_range('voltage', 12)
psu.outputs[0].voltage_level = 12.0
psu.outputs[0].current_limit = 1.0
psu.outputs[0].ovp_limit = 14.0
psu.outputs[0].ovp_enabled = True
psu.outptus[0].enabled = True
</code>