iec62056.py

#!/usr/bin/python3 

import serial
import time

echo_back=False
#echo_back=True

ser = serial.Serial('/dev/ttyUSB0', 
        300, 
        timeout=2,
        bytesize=serial.SEVENBITS, 
        parity=serial.PARITY_EVEN, 
        stopbits=serial.STOPBITS_ONE )  # open serial port

START = b'/'
END = b'!'
SOH = b'\x01'
STX = b'\x02'
ETX = b'\x03'
EOT = b'\x04'
ACK = b'\x06'
NAK = b'\x15'

def send_check(data):
    print("w", data.hex())
    ser.write(data)     # write a string
    if echo_back:
        s = ser.readline()
        print("r", s.hex())
        if data != s:
            print("Echo back failed:", s, s.hex())
            #return False
        return True
    else:
        time.sleep((1/ser.baudrate)*9*len(data)+0.1)
        return True

# B1 Wakeup
def wakeup():
    start = time.time()
    while time.time() < start + 2.2:
        send_check(b'\00')
    time.sleep(1.5)

# 6.4.3.1
def data_readout():
    # send ACK and set mode
    if not send_check(ACK + b"050\r\n"):
        raise("ACK failed")
    
    ser.baudrate = 9600
    
    s = ser.read_until(expected=ETX, size=None)
    print(s[1:-1].decode("utf-8"), s.hex())
    
    send_check(SOH + b"\xb0" + ETX + b"q")

#wakeup()

if not send_check(b"/?!\r\n"):
    raise("start failed")

# readback ID
s = ser.readline()
print(s, s.hex())
if len(s) < 1:
    #raise("no id received")
    pass

data_readout()

ser.close()