CommFujiExamplePython2.6.py

#!/usr/bin/env python
#####################################################################################
# COMM TEST PROGRAM FOR FUJI PXG4 or PXR3 with RS485 option and modbus protocol
# This program shows how to read Temp from a Fuji PID
# ##################################################################################################

# REQUIREMENTS
# python 2.6 : http://www.python.org/ftp/python/2.6.2/python-2.6.2.msi
# pyserial for python 2.6: http://sourceforge.net/projects/pyserial/files/pyserial/2.5/pyserial-2.5-rc1.win32.exe/download
# javacomm: http://www.xpl4java.org/xPL4Java/javacomm.html
# Java JDK or JRE:  http://java.sun.com/javase/downloads/index.jsp

import serial
import time
import binascii


def main():

    #Read temperature in a forever loop to check operation

    delay = 2            # set time between each reading in seconds
    deci = 10.           # if decimal position in PID is 1, then divide by 10 the temperature        
    start = time.time()  # time 

    print "Press <CTRL 'C'> to stop"
    
    while True:    
        t = temperature()/deci               # read present temperature 
        print str(t)                         # output temperature
        time.sleep(delay)                    # wait delay before next reading in while loop
    

#TEMPERATURE function reads the temperature and compares it with the CRC16 received. Returns an int
def temperature():

    #PART A: Here we send the command to read temp and read the receive data in to r.
    serPID = None
    try:
        # chose either a command for unit #1 or or a command for unit #2
        #command for unit id = 1
        #command = "\x01\x04\x03\xE8\x00\x01\xB1\xBA"
        
        #command for unit id = 2
        command = "\x02\x04\x03\xE8\x00\x01\xB1\x89"
        
        serPID = serial.Serial("COM12", baudrate=9600, bytesize=8, parity='O', stopbits=1, timeout=1)
        serPID.write(command)
        #example of data received r = "\x01\x04\x02\x03\x46\x38\x32" (7 bytes)
        r = serPID.read(7)     
        serPID.close()
        
        if len(r) != 7:
            print "bad RX data"
            return 0

    except serial.SerialException, e:
        print "Serial port error" + str(e)
        
    finally:
        if serPID:
            serPID.close()

    #PART B: Here we extract the value of the CRC16 sent by finding the sum of the last two bytes (bin to hex; then hex to int)
    crcRx =  int(binascii.hexlify(r[-1]+r[-2]),16) 

    #PART C: Here we calculate our own value of the CRC16 from the data we received (r minus last two bytes)
    crcCal1 = fujiCrc16(r[:-2])                                
    
    #PART D: We compare PART B with PART C. Return temperature if OK else print crc16 Error and return 0 
    if crcCal1 == crcRx: #crcRx:
        # convert data part binary string to hex representation
        s1 = binascii.hexlify(r[3] + r[4])
        #conversion from hex to dec
        return int(s1,16)
    else:
        print "bad crc16 sum"
        return 0


#FUJICRC16 function calculates the CRC16 of the data. It expects a binary string as input and returns and int
def fujiCrc16(string):  
    crc16tab = (0x0000,
                0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
                0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880,
                0xC841, 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0,
                0x1C80, 0xDC41, 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100,
                0xD1C1, 0xD081, 0x1040, 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, 0x3600, 0xF6C1, 0xF781, 0x3740,
                0xF501, 0x35C0, 0x3480, 0xF441, 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, 0xFA01, 0x3AC0, 0x3B80,
                0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, 0xEE01, 0x2EC0,
                0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40, 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, 0x2200,
                0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041, 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
                0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441, 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80,
                0xAE41, 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840, 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0,
                0x7A80, 0xBA41, 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40, 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700,
                0xB7C1, 0xB681, 0x7640, 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041, 0x5000, 0x90C1, 0x9181, 0x5140,
                0x9301, 0x53C0, 0x5280, 0x9241, 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440, 0x9C01, 0x5CC0, 0x5D80,
                0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, 0x8801, 0x48C0,
                0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, 0x4400,
                0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040)
    
    cr=0xFFFF 
    for j in string:
        tmp = cr ^(ord(j))
        cr =(cr >> 8)^crc16tab[(tmp & 0xff)]

    return cr
    
    
main()