#!/usr/bin/python2.7
#
# Just a quick n' dirty script to read the Data from a VA18B multimeter.
# This DMM uses the low nibble of 14 bytes to send the lcd segments.
#
# License: GPL v3. http://www.gnu.org/licenses/gpl-3.0-standalone.html
#
import signal
import sys
import time
import serial
import io
import getopt
interval = '1.0'
device = '/dev/ttyUSB0'
def showhelp():
print ' va18b.py -i <time in secs> -d <device>'
print ' Eg: va18b.py -i 1.5 -d /dev/ttyUSB1'
try:
opts, args = getopt.getopt(sys.argv[1:],"hd:i:",['help'])
except getopt.GetoptError:
print 'Error: -i, -d option require a value.'
showhelp()
sys.exit(1)
for opt, arg in opts:
if opt in ('-h','--help'):
showhelp()
sys.exit(1)
if opt == '-i':
interval = arg
if opt == '-d':
device = arg
try:
port=serial.Serial(port=device,
baudrate=2400,
bytesize=serial.EIGHTBITS,
stopbits=serial.STOPBITS_ONE,
parity=serial.PARITY_NONE,
timeout=None)
if not port.isOpen():
port.open()
except IOError,err:
print '\nError:' + str(err) + '\n'
sys.exit(1)
def signal_handler(signal, frame):
sys.stderr.write('\n\nYou pressed Ctrl+C!\n\n')
port.flushInput()
port.close()
sys.exit(0)
signal.signal(signal.SIGINT, signal_handler)
# Every packet is 14 bytes long.
def get_bytes():
i=0
substr=''
while i<=13:
byte=port.read(1)
# converting every byte to binary format keeping the low nibble.
substr += '{0:08b}'.format(ord(byte))[4:]
i += 1
return substr
def stream_decode(substr):
ac = int(substr[0:1])
dc = int(substr[1:2])
auto = int(substr[2:3])
pclink = substr[3:4]
minus = int(substr[4:5])
digit1 = substr[5:12]
dot1 = int(substr[12:13])
digit2 = substr[13:20]
dot2 = int(substr[20:21])
digit3 = substr[21:28]
dot3 = int(substr[28:29])
digit4 = substr[29:36]
micro = int(substr[36:37])
nano = int(substr[37:38])
kilo = int(substr[38:39])
diotst = int(substr[39:40])
mili = int(substr[40:41])
percent = int(substr[41:42])
mega = int(substr[42:43])
contst = int(substr[43:44])
cap = int(substr[44:45])
ohm = int(substr[45:46])
rel = int(substr[46:47])
hold = int(substr[47:48])
amp = int(substr[48:49])
volts = int(substr[49:50])
hertz = int(substr[50:51])
lowbat = int(substr[51:52])
minm = int(substr[52:53])
fahrenh = substr[53:54]
celcius = int(substr[54:55])
maxm = int(substr[55:56])
digit = {"1111101":"0",
"0000101":"1",
"1011011":"2",
"0011111":"3",
"0100111":"4",
"0111110":"5",
"1111110":"6",
"0010101":"7",
"1111111":"8",
"0111111":"9",
"0000000":"",
"1101000":"L"}
value = ("-" if minus else " ") +\
digit.get(digit1,"") + ("." if dot1 else "") +\
digit.get(digit2,"") + ("." if dot2 else "") +\
digit.get(digit3,"") + ("." if dot3 else "") +\
digit.get(digit4,"")
flags = " ".join(["AC" if ac else "",
"DC" if dc else "",
"Auto" if auto else "",
"Diode test" if diotst else "",
"Conti test" if contst else "",
"Capacity" if cap else "",
"Rel" if rel else "",
"Hold" if hold else "",
"Min" if minm else "",
"Max" if maxm else "",
"LowBat" if lowbat else ""])
units = ("n" if nano else "") +\
("u" if micro else "") +\
("k" if kilo else "") +\
("m" if mili else "") +\
("M" if mega else "") +\
("%" if percent else "") +\
("Ohm" if ohm else "") +\
("Amp" if amp else "") +\
("Volt" if volts else "") +\
("Hz" if hertz else "") +\
("C" if celcius else "")
return value + " " + flags + " " + units
sys.stderr.write('Press Ctrl+C to exit.\n\n')
while 1:
substr = get_bytes()
data = stream_decode(substr)
print data
time.sleep(float(interval))
port.flushInput()
