USB Relay switching through HID

usb-relay.py

import hid
import re

class Relay:
    def __init__(self, debug=False):
        # USBrelay<relay-count>
        self.vendor_id = 0x16c0
        self.product_id = 0x05df

        self.debug = debug

        self.ON = 0xff
        self.OFF = 0xfd

        self.devices = hid.enumerate(self.vendor_id, self.product_id)
        self.device = hid.device()
        self.verbose('Opening device')
        try:
            self.device.open(self.vendor_id, self.product_id)
        except IOError as e:
            print(e)

    def verbose(self, txt):
        if self.debug is True:
            print(txt)

    def close(self):
        self.device.close()

    def get_channels(self):
        match = re.search('(\d+)$', self.device.get_product_string())
        self.verbose('Found ' + match.group(0) + ' relay switches')
        return match.group(0)

    def toggle(self, channel):
        if self.is_on(channel):
            self.off(channel)
        else:
            self.on(channel)

    def on(self, channel):
        buf = (0x0, self.ON, channel, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
        self.device.write(buf)

    def off(self, channel):
        buf = (0x0, self.OFF, channel, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
        self.device.write(buf)

    def is_on(self, channel):
        fr = self.device.get_feature_report(channel, 8)
        state = fr[7]
        if state == 0:
            return False
        if channel == 1:
            if state == 1 or state == 3:
                return True
            else:
                return False
        if channel == 2:
            if state == 2 or state == 3:
                return True
            else:
                return False

    @staticmethod
    def print_all_devices():
        for d in hid.enumerate():
            keys = list(d.keys())
            keys.sort()
            for key in keys:
                print(repr(key).ljust(25), ':', d[key])
            print("---------------------------------------------------------")

    def print_relays(self):
        for d in hid.enumerate(self.vendor_id, self.product_id):
            keys = list(d.keys())
            keys.sort()
            for key in keys:
                print(repr(key).ljust(25), ':', d[key])
            print("---------------------------------------------------------")