I'm trying to control an SR830 lock-in amplifier (LIA) with Python script. I am using the packages PyMeasure and PyVISA. My connection is USB to RS232. I can write commands to the LIA but when I try to read from the LIA I get the error below.
Note: I believe the issue is the rv value; it is supposed to be >0 but it looks like its

-1073807339. ​

I think I have defined the serial port parameters correctly:
adapter = VISAAdapter('ASRL3::INSTR', baud_rate=9600, data_bits=8, flow_control=1, parity=Parity.none, stop_bits=StopBits.one)
Like I said, I can write just fine but reading is the issue. Maybe I need to install a driver or change something about how to interpret the message from the LIA?
I didn't change the instrument.py, visa.py, messagebased.py, highlevel.py codes, they came with the packages.
Any help is appreciated, thank you.

VisaIOError Traceback (most recent call last)
<ipython-input-3-275122865b50> in <module>
----> 1 LIA.ask("*IDN?")
2 print ("ok")

C:\ProgramData\Anaconda3\lib\site-packages\pymeasure\instruments\instrument.py in ask(self, command)
90 :param command: command string to be sent to the instrument
91 """
---> 92 return self.adapter.ask(command)
93
94 def write(self, command):

C:\ProgramData\Anaconda3\lib\site-packages\pymeasure\adapters\visa.py in ask(self, command)
110 :returns: String ASCII response of the instrument
111 """
--> 112 return self.connection.query(command)
113
114 def ask_values(self, command, **kwargs):

C:\ProgramData\Anaconda3\lib\site-packages\pyvisa\resources\messagebased.py in query(self, message, delay)
642 time.sleep(delay)
643
--> 644 return self.read()
645
646 def query_ascii_values(

C:\ProgramData\Anaconda3\lib\site-packages\pyvisa\resources\messagebased.py in read(self, termination, encoding)
484 if termination is None:
485 termination = self._read_termination
--> 486 message = self._read_raw().decode(enco)
487 else:
488 with self.read_termination_context(termination):

C:\ProgramData\Anaconda3\lib\site-packages\pyvisa\resources\messagebased.py in _read_raw(self, size)
440 status,
441 )
--> 442 chunk, status = self.visalib.read(self.session, size)
443 ret.extend(chunk)
444 except errors.VisaIOError as e:

C:\ProgramData\Anaconda3\lib\site-packages\pyvisa_py\highlevel.py in read(self, session, count)
517 )
518
--> 519 return data, self.handle_return_value(session, status_code)
520
521 def write(self, session: VISASession, data: bytes) -> Tuple[int, StatusCode]:

C:\ProgramData\Anaconda3\lib\site-packages\pyvisa\highlevel.py in handle_return_value(self, session, status_code)
249
250 if rv < 0:
--> 251 raise errors.VisaIOError(rv)
252
253 if rv in self.issue_warning_on:

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

 

I can write just fine

Which does this mean:

a. I can run python code which is supposed to write to the SR830 and I can see on the SR830 that the write
had the effect it was supposed to.

b. I can run python code which is supposed to write to the SR830 and I don't get a python error message.

SR830: https://www.thinksrs.com/products/sr810830.html
PyVISA: https://pyvisa.readthedocs.io/en/latest/
PyMeasure: https://github.com/pymeasure/pymeasure

Appears to be Anaconda on windows...

 

I can set the LIA frequency using the Python code. I say LIA.frequency=10000 and the frequency output actually becomes 10000 Hz.

 

Great! That would mean to me that you are talking to the correct device at the correct baud rate.

 

"

a. I can run python code which is supposed to write to the SR830 and I can see on the SR830 that the write
had the effect it was supposed to.​

"

I can set the LIA frequency using the Python code. I say LIA.frequency=10000 and the frequency output actually becomes 10000 Hz.​

Looking at Device Manager under Ports (COM & LPT), it shows the USB (COM10) and says that I have the Prolific driver installed and "this device is working properly". The cable is the Tripp-Lite

U209-005-DB25 https://www.tripplite.com/support/u209005db25#section-downloads.​