handle the error

[deanhystad]

I would start by understanding what is going on when the Value Error exception is raised. What is returned by receive()? Maybe start with something like this:

def get_dcv(self):
    self.connector.send('DCV?')
    try:
        value = self.connector.receive()
        return float(value)
    except ValueError:
        print(f"Expecting a float but got '{value}'")
    return 0

Now you can see what you get when this error occurs. Do the non-float return values contain important information?