[Python] Timeout error with pyvisa when using GPIB connection

I am currently using a DPO 7054 Digital Phospore Oscilloscope to record the voltage of two single-photon detectors. A GPIB connection allows for the transfer of the waveforms towards my PC from which I analyse the data. I use pyvisa to communicate with the oscilloscope.

My problem relies on the fact that I sometimes get a timeout error such as: "VI_ERROR_TMO (-1073807339): Timeout expired before operation completed". I do not understand why or when it happens, but after this error I can not re-communicate with the oscilloscope unless I turn it off and on again.

Here is a code I use to start and stop the communication with the resource and check errors :

import pyvisa
import time
def p():
time.sleep(1)
return (print("Toc"))

rm = pyvisa.ResourceManager() #Create Ressource Manager object
rm.close()
rm = pyvisa.ResourceManager() #Create Ressource Manager object
print("\n",rm.list_resources()) #Gives tuple with available resources
print(rm,": Ressource Manager Object\n") # Check what backend is used and the location of the shared library used, if relevant
print('\a')
#%%
os = rm.open_resource('GPIB0::1::INSTR')
os.flush(pyvisa.constants.VI_READ_BUF)
os.clear()
os.close()
#%%
rm = pyvisa.ResourceManager()
os = rm.open_resource('GPIB0::1::INSTR',
read_termination = '\n')

os.write("*IDN?")
print(os.read_raw())
#data = os.read_values(1000)
print(os.query("*IDN?"))

os.write("ACQuire:STATE STOP")
os.write("ACQuire:STATE RUN")

print(("xinc ",os.query("WFMPRE:XINCR?")))
print("xincr ",float(os.query("WFMPRE:XINCR?")))
print("xzero ",os.query("WFMPRE:XZERO?"))
print("pt_off ",os.query("WFMPRET_OFF?"))
print("horiz pos ",os.query("HORIZONTALOS?"))

print("ymult ",os.query('WFMPRE:YMULT?')) # y-axis least count,volts / level
print("yzero ",os.query('WFMPRE:YZERO?')) # y-axis zero error,reference voltage
print("yoff ",os.query('WFMPRE:YOFF?')) # y-axis offset,reference position (level)


if False:


print(rm.session)
os.timeout = 1e4 #in ms. For infinite timeout, set None or float('+inf')
print(os.query('*IDN?'))
os.write('*IDN?')
print(os.read_raw(1))

print(rm.session)

os.write('*ESR?')
print(os.read_raw(1))
a = time.time()
os.write("ALLEV?")
b = time.time()
print(os.read_raw(1))
c = time.time()

print("\n",(b-a)*1e3,(c-a)*1e3)
os.clear()
os.close()
rm.close()


If I have already encountered a TIMEOUT error, then the code will only print:

('ASRL 3::INSTR', 'ASRL4::INSTR', 'GPIB0::1::INSTR')
Resource Manager of Visa Library at C:\WINDOWS\system32\visa32.dll : Ressource Manager Object


and send the following traceback :

Traceback (most recent call last):

File C:\ProgramData\anaconda3\Lib\site-packages\spyder_kernels\py3compat.py:356 in compat_exec
exec(code, globals, locals)

File c:\users\python\close gpib.py:31
os.write("*IDN?")

File ~\AppData\Roaming\Python\Python312\site-packages\pyvisa\resources\messagebased.py:196 in write
count = self.write_raw(message.encode(enco))

File ~\AppData\Roaming\Python\Python312\site-packages\pyvisa\resources\messagebased.py:156 in write_raw
return self.visalib.write(self.session, message)[0]

File ~\AppData\Roaming\Python\Python312\site-packages\pyvisa\ctwrapper\functions.py:2795 in write
ret = library.viWrite(session, data, len(data), byref(return_count))

File ~\AppData\Roaming\Python\Python312\site-packages\pyvisa\ctwrapper\highlevel.py:226 in _return_handler
return self.handle_return_value(session, ret_value) # type: ignore

File ~\AppData\Roaming\Python\Python312\site-packages\pyvisa\highlevel.py:251 in handle_return_value
raise errors.VisaIOError(rv)

VisaIOError: VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.


What am I doing wrong? How can I stop the TIMEOUT error from happening? Or if it happens, how can I re-run my code without having to turn on and off the oscilloscope?

Thank you for your time.

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