A Python DSL and command line util for controlling the subset of functionality I use on my NAD C355BEE analog stereo amp through its RS232 connection

amp.py

#!/usr/bin/python

import serial
import sys


class Amp(object):

    def __init__(self):
        self._port = serial.Serial(
            port='/dev/ttyUSB0', baudrate=115200, timeout=0.2)

    def __getattr__(self, name):
        key = 'Main.%s' % name
        self._port.write('\n%s?\n' % key)
        return self._port.readline().strip().replace('%s=' % key, '')

    def __setattr__(self, name, value):
        if name.startswith('_'):
            self.__dict__[name] = value
            return
        key = 'Main.%s' % name
        self._port.write('\n%s=%s\n' % (key, value))
        result = self._port.readline().strip().replace('%s=' % key, '')
        print '%s=%s %s' % (
            name, value,
            'OK' if result.lower() == value.lower() else 'failed')

    def __add__(self, other):
        for i in range(other):
            self._port.write('\nMain.Volume+\n')
            result = self._port.readline().strip() == 'Main.Volume+'
            print 'Volume+ %s' % ('OK' if result else 'failed')

    def __sub__(self, other):
        for i in range(other):
            self._port.write('\nMain.Volume-\n')
            result = self._port.readline().strip() == 'Main.Volume-'
            print 'Volume- %s' % ('OK' if result else 'failed')



if __name__ == '__main__':
    if len(sys.argv) != 2:
        sys.exit('Usage: %s (video|disc|cd|+N|-N)' % sys.argv[0])

    arg = sys.argv[1]

    amp = Amp()
    if arg.lower() in ('video', 'disc', 'cd'):
        amp.Power = 'On'
        amp.SpeakerA = 'On'
        amp.SpeakerB = 'Off'
        amp.Source = arg
    elif arg.startswith('+'):
        amp + int(arg[1:])
    elif arg.startswith('-'):
        amp - int(arg[1:])