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Load and read Arb signal into wave generator using pyhton and usbtmc in linux?

Question asked by ishoro13 on Jan 23, 2017
Latest reply on May 14, 2017 by Benj001

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I need to load chirp signal shown in Fig1 into wave generator(Agilent Technologies,33621A).

Code used to generate Chirp Signal: http://paste2.org/JxBPmXFk

Code to drive wave generator via usbtmc (Sample code to call the built-in arb wafeform SINC in Burst Mode): http://paste2.org/aFGAecYb

Where imported instrument:http://paste2.org/7Yf22D4C

I have used the following list of commands to create sample code: http://literature.cdn.keysight.com/litweb/pdf/33500-90901.pdf?id=2197440

The question is how to load created chirp signal into wave generator?

ishoro13 Jan 26, 2017 6:41 AM

Correct Answer

hognala - thank you very much for all your help, the code is now working:

import instrument
import time
from scipy import signal
from scipy.signal import chirp
import scipy as sp
import numpy as np 
import array
import matplotlib.pyplot as plt # import matplotlib.pyplot as plot
### CHIRP
fs = 10e6;fc= 50e6;dt = 1e-6;ts = 1e9; # GigaSamples/Second
N = ts/1e6;step = 1./N; # N Samples in MicroSecond
t = np.arange(0,1+step,step )*dt;
# CHIRP
chirp_w = chirp(t, f0=fs, f1=fc, t1=np.max(t), method='linear');
# TUKEY
tukey_w = signal.tukey(len(chirp_w));
# TUKEY*CHIRP
chirp_tukey_w = tukey_w*chirp_w;
######Waveform Genertor 
wavegen = instrument.usbtmc("/dev/usbtmc2");
# Drive the Wave Generator
wavegen.write("*IDN?");
print wavegen.read(100);
wavegen.write('*RST;*CLS;*OPC?') #reset instrument
time.sleep(2) #wait 2 seconds for the reset to complete
wavegen.read(1000) #read *OPC? response
wavegen.write('SOUR1:DATA:VOL:CLE') #clear volatile waveforms
wavegen.write('SOUR1:FUNC ARB') #tell the instrument to use the arb feature
dataString = "DATA:ARB CHIRP"
for datapoint in chirp_tukey_w :
 dataString +=","+ str(datapoint) 
wavegen.write(dataString)
wavegen.write('SOUR1:FUNC:ARB CHIRP')
#set some parameters for the arb and output it
wavegen.write('SOUR1:VOLT 2.5') # 
wavegen.write('SOUR1:VOLT:OFFS 0')
wavegen.write('OUTP1:LOAD 50')
wavegen.write('SOUR1:FUNC:ARB:SRAT 1e9') 
wavegen.write('SOUR1:BURS:STAT ON') #need to set burst rate before turning on
wavegen.write('SOUR1:BURS:INT:PER 20e-6')
wavegen.write('OUTP1 ON')
wavegen.write('MMEM:STORE:DATA "INT:\CHIRP.arb"')

Notes for new users:

min/max of Arb signal is only from +1 to -1
minimum of 32 points (33600 Series) and up to 1,000,000 points, if you will use less than 32 you will have an error "+882, Arb: Segment too small"
you can find more examples in http://literature.cdn.keysight.com/litweb/pdf/33500-90901.pdf?id=2197440 page 241.
to see an error in the waveform generator, press: "System -> Help -> 2. View remote command error queue." (List of Error Messages starts on page 448.)

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hognala

Jan 24, 2017 11:51 AM

This is the code I came up with. Note, I commented out the line for burst, and the sample rate, because they still need some tuning (see comments):

# Drive the Wave Generator
wavegen = instrument.Keysight33600A("/dev/usbtmc0")
wavegen.write('*RST;*CLS;*OPC?')      #reset instrument
time.sleep(2)                         #wait 2 seconds for the reset to complete
wavegen.read(1000)                    #read *OPC? response
wavegen.write('SOUR1:DATA:VOL:CLE')   #clear volatile waveforms
wavegen.write('SOUR1:FUNC ARB')       #tell the instrument to use the arb feature

#use the chirp_w signal, format it for the instrument, send to instrument
dataString = 'SOUR1:DATA:ARB1 chirp_w'
for datapoint in chirp_w:
    dataString += ',' + str(datapoint) 
wavegen.write(dataString)
wavegen.write('SOUR1:FUNC:ARB chirp_w')

   
#set some parameters for the arb and output it
wavegen.write('SOUR1:VOLT 2') # 
wavegen.write('SOUR1:VOLT:OFFS 0')
wavegen.write('OUTP1:LOAD 50')
#wavegen.write('SOUR1:BURS:STAT ON')      #need to set burst rate before turning on
#wavegen.write('SOUR1:FUNC:ARB:SRAT fs')  #need to provide a value, not 'fs' 

wavegen.write('OUTP1 ON')

Also, check out the 33600 programming guide. A lot of the commands are different than the 33200 guide you referenced - http://www.keysight.com/main/redirector.jspx?action=ref&cname=EDITORIAL&ckey=2197440&lc=eng&cc=US&nfr=-32907.1082253.00

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ishoro13 @ hognala on Jan 24, 2017 12:22 PM

Dear hognala,

Thank you so much for the effort. The code is not working YET, but I think the problem is that someone is already uploaded four (maximum) user-defined waveforms. As us can see in the attached image photo bellow:

I have tried to delete them using following command:

wavegen.write('SOUR1:DATA:DELL:ALL') #

But nothing changed.

Should I use something like in the following code:

wavegen.write('MMEM:LOAD:DATA "INT:\BUILTIN\CHIRP_B.arb')

One more time thank you so much for helping me!

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hognala

@ ishoro13 on Jan 24, 2017 12:28 PM

I think you want this command:

wavegen.write('MMEM:DEL "INT:\BUILTIN\CHIRP_B.arb"')

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ishoro13 @ hognala on Jan 25, 2017 4:14 AM

Yes, you are right, but without \BUILTIN\ but it's my fault for giving you the wrong directory in first place.

So it should be:

wavegen.write('MMEM:DEL "INT:\CHIRP_B.arb"')

I have deleted all old files, but the code is still not working, and it's very confusing.

The full code which I'm using right now is following:

import numpy as np
from scipy.signal import chirp
from scipy import signal
import array
import instrument

# variables
fs = 5e6;
fc= 50e6;
dt = 1e-6;
ts = 1e9; # GigaSamples/Second
N = ts/1e6; # N Samples in MicroSecond
step = 1./N;
t = np.arange(0,1+step,step )*dt;
# CHIRP
chirp_w = chirp(t, f0=fs, f1=fc, t1=np.max(t), method='linear');
# TUKEY
tukey_w = signal.tukey(len(chirp_w));
# TUKEY*CHIRP
chirp_tukey_w = tukey_w*chirp_w;
# zeros for 'Burst Mode' 20*e-6 seconds
zeros_w = np.zeros(N*20); 
# CHIRP in 'Burst Mode'
bursted_w = [];
bursted_w.extend(chirp_tukey_w);
bursted_w.extend(zeros_w);
 
# Drive the Wave Generator
wavegen = instrument.Keysight33600A("/dev/usbtmc2")
wavegen.write('*RST;*CLS;*OPC?') #reset instrument
time.sleep(2) #wait 2 seconds for the reset to complete
wavegen.read(1000) #read *OPC? response
wavegen.write('SOUR1:DATA:VOL:CLE') #clear volatile waveforms
wavegen.write('SOUR1:FUNC ARB') #tell the instrument to use the arb feature
#use the chirp_tukey_w signal, format it for the instrument, send to instrument
dataString = 'SOUR1:DATA:ARB1 chirp_tukey_w'
for datapoint in chirp_tukey_w:
dataString += ',' + str(datapoint) 
wavegen.write(dataString)
wavegen.write('SOUR1:FUNC:ARB chirp_tukey_w')

#set some parameters for the arb and output it
wavegen.write('SOUR1:VOLT 2') # 
wavegen.write('SOUR1:VOLT:OFFS 0')
wavegen.write('OUTP1:LOAD 50')
wavegen.write('SOUR1:BURS:STAT ON') #need to set burst rate before turning on
#wavegen.write('SOUR1:FUNC:ARB:SRAT fs') #need to provide a value, not 'fs'
wavegen.write('OUTP1 ON')
wavegen.write('SOUR1:BURS:INT:PER 20')

However the length of my signal is 15676 and obviously string:

>>> len(dataString)
15676

>>> type(dataString)
<type 'str'>

May be signal is to long (according to the book it's acceptable value).

Or should I download the signal is binary block or as list of values.

Note: the usbtmc2 changed because of oscilloscope. So my scope now is usbtmc0.

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hognala

@ ishoro13 on Jan 24, 2017 12:59 PM

Can you take a picture of the instrument front panel, so we can see how far it got?

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ishoro13 @ hognala on Jan 24, 2017 1:05 PM

Please find attached image bellow:

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ishoro13 @ hognala on Jan 25, 2017 6:32 AM

I'm wondering, if you have any ideas, why I can't load an arb signal?

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ishoro13 @ hognala on Jan 25, 2017 6:16 AM

Also I have the same error all the time: "+882, Arb: Segment too small"

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hognala

@ ishoro13 on Jan 25, 2017 7:19 AM

Are you missing a tab/spaces at this line (or is that just an artifact of how the code looks on the forum?)?

for datapoint in chirp_tukey_w:
dataString += ',' + str(datapoint)

Should be:

for datapoint in chirp_tukey_w:
    dataString += ',' + str(datapoint)

Try printing out the first couple hundred characters of the string and see if they look ok. Also, make sure your min/max of the signal is only from +1 to -1

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ishoro13 Jan 26, 2017 6:41 AM

hognala - thank you very much for all your help, the code is now working:

import instrument
import time
from scipy import signal
from scipy.signal import chirp
import scipy as sp
import numpy as np 
import array
import matplotlib.pyplot as plt # import matplotlib.pyplot as plot
### CHIRP
fs = 10e6;fc= 50e6;dt = 1e-6;ts = 1e9; # GigaSamples/Second
N = ts/1e6;step = 1./N; # N Samples in MicroSecond
t = np.arange(0,1+step,step )*dt;
# CHIRP
chirp_w = chirp(t, f0=fs, f1=fc, t1=np.max(t), method='linear');
# TUKEY
tukey_w = signal.tukey(len(chirp_w));
# TUKEY*CHIRP
chirp_tukey_w = tukey_w*chirp_w;
######Waveform Genertor 
wavegen = instrument.usbtmc("/dev/usbtmc2");
# Drive the Wave Generator
wavegen.write("*IDN?");
print wavegen.read(100);
wavegen.write('*RST;*CLS;*OPC?') #reset instrument
time.sleep(2) #wait 2 seconds for the reset to complete
wavegen.read(1000) #read *OPC? response
wavegen.write('SOUR1:DATA:VOL:CLE') #clear volatile waveforms
wavegen.write('SOUR1:FUNC ARB') #tell the instrument to use the arb feature
dataString = "DATA:ARB CHIRP"
for datapoint in chirp_tukey_w :
 dataString +=","+ str(datapoint) 
wavegen.write(dataString)
wavegen.write('SOUR1:FUNC:ARB CHIRP')
#set some parameters for the arb and output it
wavegen.write('SOUR1:VOLT 2.5') # 
wavegen.write('SOUR1:VOLT:OFFS 0')
wavegen.write('OUTP1:LOAD 50')
wavegen.write('SOUR1:FUNC:ARB:SRAT 1e9') 
wavegen.write('SOUR1:BURS:STAT ON') #need to set burst rate before turning on
wavegen.write('SOUR1:BURS:INT:PER 20e-6')
wavegen.write('OUTP1 ON')
wavegen.write('MMEM:STORE:DATA "INT:\CHIRP.arb"')

Notes for new users:

min/max of Arb signal is only from +1 to -1
minimum of 32 points (33600 Series) and up to 1,000,000 points, if you will use less than 32 you will have an error "+882, Arb: Segment too small"
you can find more examples in http://literature.cdn.keysight.com/litweb/pdf/33500-90901.pdf?id=2197440 page 241.
to see an error in the waveform generator, press: "System -> Help -> 2. View remote command error queue." (List of Error Messages starts on page 448.)

2 people found this helpful

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