Lakeshore 336 Communication problem

[CosimoTommasi]

I'm trying to interface with a Lakeshore 336 temperature controller via Ethernet connection. I can do so by using NI MAX or the instrument web interface. However, when I try to load that instrument to my station in qcodes I get an error.

Here is my script:

import qcodes as qc
station = qc.Station(config_file='Init_station.yaml')
tcontrol=station.load_instrument('tcontrol')

and here is the relevant content of my .yaml file:

tcontrol: 
        type: qcodes.instrument_drivers.Lakeshore.Model_336.Model_336 
        address: 'TCPIP0::169.254.94.114::7777::SOCKET'
        enable_forced_reconnect: true
        init:
            terminator: \r\n
            timeout: 1.0

Now, when I try to run the code I get the following error:

[tcontrol(Model_336)] Error getting or interpreting *IDN?: ''
Traceback (most recent call last):
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\qcodes\instrument\instrument.py", line 91, in get_idn
    idstr = self.ask("*IDN?")
            ^^^^^^^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\qcodes\instrument\instrument.py", line 424, in ask
    raise e
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\qcodes\instrument\instrument.py", line 417, in ask
    answer = self.ask_raw(cmd)
             ^^^^^^^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\qcodes\instrument\visa.py", line 329, in ask_raw
    response = self.visa_handle.query(cmd)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\pyvisa\resources\messagebased.py", line 648, in query
    return self.read()
           ^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\pyvisa\resources\messagebased.py", line 486, in read
    message = self._read_raw().decode(enco)
              ^^^^^^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\pyvisa\resources\messagebased.py", line 442, in _read_raw
    chunk, status = self.visalib.read(self.session, size)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\pyvisa\ctwrapper\functions.py", line 2337, in read
    ret = library.viRead(session, buffer, count, byref(return_count))
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\pyvisa\ctwrapper\highlevel.py", line 226, in _return_handler
    return self.handle_return_value(session, ret_value)  # type: ignore
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\LocalAdmin\Anaconda3\envs\testQcodes\Lib\site-packages\pyvisa\highlevel.py", line 251, in handle_return_value
    raise errors.VisaIOError(rv)
pyvisa.errors.VisaIOError: ('VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.', "asking '*IDN?' to <Model_336: tcontrol>")

I tried using NI MAX to query '*IDN?' and I correctly get model number and firmware version (provided I specify the termination character). However, I tried reading via NI MAX the Status Byte and got the following error:

Read STB Operation
Error

VISA:  (Hex 0xBFFF003A) Unable to start operation because setup is invalid (due to attributes being set to an inconsistent state).

I suppose this issue is linked with the communication problem of qcodes, but I don't know what to do. Any help?

[jenshnielsen]

@CosimoTommasi I am not sure the status byte is related, I think I have seen a number of instruments not implementing this. I would suggest that you test if you can connect to the instrument from python using pyvisa (which qcodes used under the hood) This will help identify if the issue is in the qcodes driver or the pyvisa comm. See https://pyvisa.readthedocs.io/en/latest/ for how to connect with pyvisa