thorlabs_sc10 failing to query

[eoinell]

https://github.com/nanophotonics/nplab/blob/a70c6d7b38b12315ec2cc98077737c6290b18710/nplab/instrument/message_bus_instrument.py#L120

Always prints ''this command did not echo!!!'' probably an encoding issue

Works fine in python 2.7.

[YagoDel]

Might be related to #75 I'll try to have a look

[wdeacon]

Have we tested many serial devices yet? The change to the default encoding to be unicode in python 3 should be problematic. So the write string may need a b to convert it, for example this should be b'mode?'

[YagoDel]

I'm running multiple serial instruments (stage.SigmaKoki.HIT, temperatureControl.LakeShore.LS331, stage.apt_vcp_motor.DC_APT, spectrometer.Acton.SP2750...), so the base code is fine in Python 3

I think the issue is that there are only two instruments that use the ignore_echo option in message_bus_instrument, and the problem with converting to Python 3 has to be in line 132, when comparing the strings.

I don't have any instrument that echos, but try replacing the current:

first_line = self.readline(timeout).strip()
if first_line == queryString:
    return self.readline(timeout).strip()
else:
    print 'This command did not echo!!!'
return first_line

with

first_line = self.readline(timeout).strip()
print(first_line, queryString, first_line==queryString)
if first_line == queryString:
    return self.readline(timeout).strip()
else:
    print 'This command did not echo!!!'
    return first_line

That should tell you what the problem is. When you fix it, lets try and link it to #75 and close two issues in one

[eoinell]

the first_line returned by

def readline(self, timeout=None): """Read one line from the serial port.""" with self.communications_lock: return self.ser_io.readline().replace(self.termination_read,"\n") https://github.com/nanophotonics/nplab/blob/4b3a3508f6fa4feb2536ced465f742aa6e9fefd6/nplab/instrument/serial_instrument.py#L108

is an empty string

[YagoDel]

readline should only return an empty string when there is nothing to read at the instrument end. Three options for what should happen after sending sc10.write('ens?') (or some other command that requires a reply):

• No reply. Then I don't think the instrument is working. Does it work through the Thorlabs software?
• Replies directly with 0 or 1. Then it is not an echoing instrument and you need to set self. ignore_echo to False
• Replies first with something like ens?, and when you read again returns 0 or 1. Then it is an echoing instrument, and the issue is with the message_bus_instrument querying