yokogawa GS200 randomly has error setting voltages

Steps to reproduce

1. run a loop where you sweep yoko.voltage
2. try this a few times, it's not clear if it's random or specific values

  File "<ipython-input-63-df8f784eae66>", line 35, in <module>
    do1d(yoko.voltage,  yoko.voltage(), -0.4, step_num, 0.01, CavPrep_Task, vna.channels.S21.trace, CavSet_Task, vna.channels.SPEC.trace)

  File "c:\users\triton2acq\qdev-wrappers\qdev_wrappers\sweep_functions.py", line 249, in do1d
    do_plots=do_plots, use_threads=use_threads)

  File "c:\users\triton2acq\qdev-wrappers\qdev_wrappers\sweep_functions.py", line 153, in _do_measurement
    _ = loop.with_bg_task(plot.update).run(use_threads=use_threads)

  File "c:\users\triton2acq\qcodes\qcodes\loops.py", line 738, in run
    self._run_wrapper()

  File "c:\users\triton2acq\qcodes\qcodes\loops.py", line 787, in _run_wrapper
    self._run_loop(*args, **kwargs)

  File "c:\users\triton2acq\qcodes\qcodes\loops.py", line 835, in _run_loop
    set_val = self.sweep_values.set(value)

  File "c:\users\triton2acq\qcodes\qcodes\instrument\parameter.py", line 417, in set_wrapper
    raise e

  File "c:\users\triton2acq\qcodes\qcodes\instrument\parameter.py", line 399, in set_wrapper
    set_function(parsed_scaled_mapped_value, **kwargs)

  File "c:\users\triton2acq\qcodes\qcodes\utils\command.py", line 177, in __call__
    return self.exec_function(*args)

  File "c:\users\triton2acq\qcodes\qcodes\instrument_drivers\yokogawa\GS200.py", line 369, in _get_set_output
    self._set_output(output_level)

  File "c:\users\triton2acq\qcodes\qcodes\instrument_drivers\yokogawa\GS200.py", line 409, in _set_output
    self.write(cmd_str)

  File "c:\users\triton2acq\qcodes\qcodes\instrument\base.py", line 611, in write
    raise e

  File "c:\users\triton2acq\qcodes\qcodes\instrument\base.py", line 607, in write
    self.write_raw(cmd)

  File "c:\users\triton2acq\qcodes\qcodes\instrument\visa.py", line 195, in write_raw
    nr_bytes_written, ret_code = self.visa_handle.write(cmd)

  File "C:\Users\Triton2acq\Anaconda3\envs\qcodes\lib\site-packages\pyvisa\resources\messagebased.py", line 207, in write
    count = self.write_raw(message.encode(enco))

  File "C:\Users\Triton2acq\Anaconda3\envs\qcodes\lib\site-packages\pyvisa\resources\messagebased.py", line 185, in write_raw
    return self.visalib.write(self.session, message)

  File "C:\Users\Triton2acq\Anaconda3\envs\qcodes\lib\site-packages\pyvisa\ctwrapper\functions.py", line 1864, in write
    ret = library.viWrite(session, data, len(data), byref(return_count))

  File "C:\Users\Triton2acq\Anaconda3\envs\qcodes\lib\site-packages\pyvisa\ctwrapper\highlevel.py", line 188, in _return_handler
    raise errors.VisaIOError(ret_value)

VisaIOError: ('VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.', "writing ':SOUR:LEV -1.84731e-01' to <GS200_ext: yoko>", 'setting yoko_voltage to -0.18473124999999999')

This happened many times for a range of values:

eg also can replace last line with

VisaIOError: ('VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.', "writing ':SOUR:LEV 1.00000e-03' to <GS200_ext: yoko>", 'setting yoko_voltage to 0.001')

You then cannot talk to it before clearing the message queue on the instrument by running

yoko.write('*CLS')

Start in qcodes/instrument_drivers/yokogawa/GS200.py at _get_set_output and _set_output, then reproduce the voltage sweep described in the issue through qdev_wrappers/sweep_functions.py. Determine why writes time out and require *CLS, and verify that repeated sweeps across the reported values complete without the timeout or leaving the instrument unable to communicate.