Control Dell P4317Q monitor over RS232

dell_P4317Q_ctrl.py

#!/usr/bin/env python3

# Control Dell P4317Q monitor over RS232
# usage examples:
# read monitor name string and brightness: ./dell_P4317Q_ctrl.py eb01 eb30
# set brightness to minimum:               ./dell_P4317Q_ctrl.py ea3000
# set brightness to maximum:               ./dell_P4317Q_ctrl.py ea30ff
# night mode:                              ./dell_P4317Q_ctrl.py eb01 ea3000 ea3133 ea4800010000



import serial, binascii, threading, shlex, sys

s=serial.Serial("/dev/ttyUSB0",9600)

def waitForPacket():
	while True:
		b = s.read()
		if b == b'\x6F':
			b = s.read()
			if b == b'\x37':
				break

def readPacket():
	while True:
		waitForPacket()
		length = s.read()[0]
		content = s.read(length)
		read_cksum = s.read()[0]
		exp_cksum = 0x6f ^ 0x37 ^ length
		for i in content:
			exp_cksum = exp_cksum ^ i
		if exp_cksum != read_cksum:
			print("[!] CKSUM mismatch", length, content, exp_cksum, read_cksum)
		else:
			return content[0], content[1], content[2], content[3:]
	

resultCodeMap = {0x00: "Success", 0x01: "Timeout", 0x02: "Parameter error", 0x03: "Not connected", 0xff: "Failure"}
def readAndPrintPacket():
	replyCode, resultCode, command, data = readPacket()
	print("ReplyCode: %02x, ResultCode: %s (%02x), Command: %02x" % (replyCode, resultCodeMap[resultCode], resultCode, command))
	print(str(data))
	print(binascii.hexlify(data))
	return replyCode, resultCode, command, data
	
def reader():
	while True:
		readAndPrintPacket()
		
def send_cmd(b):
	b = bytes([0x37, 0x51, len(b)]) + b
	cksum = 0
	for i in b:
		cksum = cksum ^ i
	out = b + bytes([cksum])
	print("sending: "+str(binascii.hexlify(out)))
	s.write(out)

if len(sys.argv) >= 2:
	for x in sys.argv[1:]:
		send_cmd(binascii.unhexlify(x))
		replyCode, resultCode, command, data = readAndPrintPacket()
		if resultCode != 0:
			sys.exit(resultCode)
	sys.exit(0)

t=threading.Thread(target=reader)
t.start()

while True:
	instr=input(">")
	args=shlex.split(instr)
	if len(args) == 0: continue
	if args[0] == "r":
		send_cmd(bytes([0xEB, int(args[1],16)]))
	elif args[0] == "w":
		send_cmd(bytes([0xEA]) + binascii.unhexlify(args[1]))
	elif args[0] == "c":
		send_cmd(binascii.unhexlify(args[1]))
	
t.stop()