Serial port logger

## Quick and dirty serial logger. Logs data received from a serial port.

## Port and baud rate selection
monitorPort = 'COM29'
monitorBaud = 115200

##
import serial
import time
import signal

terminate = False

def logger(port, baud):
	global terminate
	
	## open the port
	try:
		serialConnection = serial.Serial(port, baud, timeout=1)
	## if it fails due to I/O error (e.g. file not found)..
	except IOError:
		## complain about it
		print('The serial port ' + port + ' is not available for use. Script terminating.')
		## terminate the script
		sys.exit('The requested COM port is not available for use, therefore the script can not continue')
	## if it fails due to an unknown exception
	except:
		## complain about it
		print('An unknown error occured while trying to open ' + port)
		## return (it might be non-fatal)
		sys.exit('An unknown error occured when trying to open the COM port, therefore the script can not continue')
	
	## open the logfile
	timeString = time.strftime("%Y%m%d-%H%M%S", time.localtime())
	fileName = timeString + '_' + port[-4:] + '_receive.log'
	logFile = open(fileName, 'a+')

	## put a header in the logfile
	timeStamp = time.strftime("%Y/%m/%d %H:%M:%S", time.localtime())
	logFile.write('### Logging ' + monitorPort + ' (' + str(monitorBaud) + 'bps). Started ' + str(timeStamp) + ' ###')
	logFile.flush()
	
	## poll until terminated
	while terminate == False:
		## check if there is data available. enclose in a try because sometimes this fails.
		try:
			waitingCharacters = serialConnection.inWaiting()
		except:
			## i don't remember why this was set to 9, but serial reading is unreliable if it set to 0
			waitingCharacters = 9
			
		## if there is data available
		if waitingCharacters >= 1:
			try:
				## get the line
				line = serialConnection.readline()
			except:
				## if we didn't get the line, just go to the next loop
				break
							
			## strip endline characters and excess start/end whitespace
			cleanLine = line.decode('utf-8', errors='ignore').rstrip().replace('\n', '').replace('\r', '')
				
			## replace tabs with single spaces
			cleanLine.expandtabs(1)
				
			## only proceed if the data isn't a blank line
			if cleanLine != '':
				## log the received line
				timeStamp = time.strftime("%Y/%m/%d %H:%M:%S", time.localtime())
				logFile.write('\n[' + str(timeStamp) + '] ' + cleanLine)
				logFile.flush()
				print('\n[' + str(timeStamp) + ' RX] ' + cleanLine)
				
	## terminated, (try to) clean up
	try:
		logFile.write('### Logging ' + monitorPort + ' (' + str(monitorBaud) + 'bps). Ended ' + str(timeStamp) + ' ###')
		logFile.close()
		serialConnection.close()
	except:
		pass

## ctrl + c handling
def handle_sigint(signal, frame):
	global terminate

	print('Ctrl + C detected. Terminating..')
	terminate = True

signal.signal(signal.SIGINT, handle_sigint)

## setup a logger for the port
print('Logging ' + monitorPort + ' at ' + str(monitorBaud) + 'bps')
logger(monitorPort, monitorBaud)