#!/usr/bin/python
import sys
import tty
import serial
import time

ser = serial.Serial("/dev/ttyUSB0", 38400)

voltage = 20000
current = 0
incdec = 0

while 1:
	tdata = ser.read()
	time.sleep(1)
	data_left = ser.inWaiting()
	tdata += ser.read(data_left)
	
	out = "A%05d,12300,%05d,1,1,1B" % (voltage, current)
	print out
	ser.write(out)

	if incdec == 0:
		current = current + 1000
	else:
		current = current - 1000
		
	if current > 20000:
		current = 20000
		incdec = 1
		
	if current < 0:
		current = 0
		incdec = 0