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A Demo on how to interface with an instrument

A Demo on how to interface with an instrument#

demo

First step#

  • create a resource manager object

  • create an instance for Keysight Instruments

import time
import numpy as np
import matplotlib.pyplot as plt
import visa
rm = visa.ResourceManager()

Second Step:#

  • Understand write and read functions with pyvisa

  • Understand query function with pyvisa

  • Understand SCPI command

  • tips for quickly check SCPI command (use EXFO manual as an example)

scpicommands

Connect to Laser Source#

## Open Connection
tls = rm.open_resource('GPIB0::20::INSTR')
tls.timeout = 10000
## Reset Laser
tls.write('*RST')
complete = tls.query('*OPC?')
## Query ID
tls.query('*IDN?')

Connect to Polarization Synthesizer#

## Open Connection
polsyn = rm.open_resource('GPIB0::10::INSTR')
polsyn.timeout = 10000
## Reset Power Meter
polsyn.write('*RST')
complete = polsyn.query('*OPC?')
##Query ID
polsyn.query('*IDN?')

Connect to Power Meter#

## Open Connection
mppm = rm.open_resource('GPIB0::10::INSTR')
mppm.timeout = 10000
## Reset Power Meter
mppm.write('*RST')
complete = mppm.query('*OPC?')
##Query ID
mppm.query('*IDN?')

Setup Laser Source#

tls_wave = '1550e-9'
tls_power = '-10'
tls_mod = 1
tls_mod_freq = 100e-3
## Setup Wavelength
tls.write('SOUR0:WAVE ' + tls_wave)
## Setup Power
tls.write('SOUR0:POW:UNIT 0')
tls.write('SOUR0:POW '+ tls_power)
## Setup Modulation
## Turn On Output Power
tls.write('OUTP0:STAT 1')

Setup Polarization Synthesizer - Scramble Polarization#

polsyn.write('PCON:SCR:ENAB 1')

Setup Power Meter#

mppm_wave = '1550e-9'
## Setup Wavelength
mppm.write('SENS1:POW:WAV ' + mppm_wave)

Query Single Channel Power - ASCII#

mppm.query('READ1:POW?')

Query All Channel Power - Binary Block#

mppm.query_binary_values('READ:POW:ALL?','f',False)

Setup Power Meter for Logging Operation#

mppm_points = '1000'
mppm_avg = '1ms'

## Stop Previous Logging
mppm.write('SENs1:FUNC:STAT LOGG,STOP')
## Manual Range Mode
mppm.write('SENS1:POW:RANGE:AUTO 0')
mppm.write('SENS1:POW:GAIN:AUTO 0')
## Set Range
mppm.write('SENS1:POW:RANG 10DBM')
## CME - Continuous Measurement Trigger Mode
mppm.write('TRIG1:INPUT CME')
## Setup Logging Points and Averaging Time
mppm.write('SENS1:FUNC:PAR:LOGG %s,%s'%(mppm_points,mppm_avg))
## Change Units to Watt
mppm.write('SENS1:POW:UNIT 1')

Start Logging, Trigger Measurement, Query for Logging Complete#

## Start Logging
mppm.write('SENS1:FUNC:STAT LOGG,STAR')
## Trigger Logging
mppm.write('TRIG 1')
## Query Logging Complete
while True:
    progress = mppm.query('SENS1:FUNC:STATE?')
    print ('Chan1: ' + progress)
    time.sleep(1)
    if 'COMPLETE' in progress:
        break

Query Logging Power Measurements - Binary Block#

## Query Data
power = mppm.query_binary_values('SENS1:FUNC:RESULT?','f', False)

Stop Logging#

mppm.write('SENS1:FUNC:STAT LOGG,STOP')

Disable Polarization Scrambling#

polsyn.write('PCON:SCR:ENAB 0')

Plot Logging Data#

#Convert list to Array of Float to Plot Data
power_array = np.array(power)
#Plot Waveform
plt.plot(power_array)
plt.show()

Close Instruments#

mppm.close()
polsyn.close()
tls.close()
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