Control serial port with pyserial

Install pyserail

Use pip to install pyserail module.

pip install pyserial

Open serail port

First of all, import pyserial module.

import pyserial

Secondly, open your serial port. If you don’t know which port you are using, you can do it like this.

def open_serialport():
    PORT_NUM = 1
    while True:
        SERIAL_PORT = 'COM%d' % PORT_NUM
        try:
            ser = serial.Serial(port=SERIAL_PORT,baudrate=1048576,parity='N',bytesize=8,stopbits=1,timeout=0)
            print "OPEN SERIAL PORT ON %s" % SERIAL_PORT
            return ser
        except Exception,e:
            PORT_NUM = PORT_NUM + 1

Send data package

In my case, I need to send binary data to a device through serail port. I use the struct module to do this.

import struct

senddata = "0015FEFF01FFFFFF0100010000020500"
str2 = ""

while True:
    if senddata:
         str1 = senddata[0:2]
         s = int(str1,16)
         str2 += struct.pack('B',s)
         senddata = senddata[2:]
    else:
        ser.write(str2)
        print repr(str2)
        time.sleep(2)
        ack = ser.read(100)
        print repr(ack)

Unpack binary data

for bdata in ack:
    ddata, = struct.unpack('B',bdata)
    print "%02x" % ddata