python串口操作_Python串口操作库pyserial(1)
测试过程中需要用到串口，目前采用pyserial库。
1 采用命令行安装pyserial库： pip install pyserial
import sys
import glob
import serial
def serial_ports():
""" Lists serial port names:raises EnvironmentError:On unsupported or unknown platforms:returns:A list of the serial ports available on the system"""
if sys.platform.startswith('win'):
ports = ['COM%s' % (i + 1) for i in range(256)]
elif sys.platform.startswith('linux') or sys.platform.startswith('cygwin'):
# this excludes your current terminal "/dev/tty"
ports = glob.glob('/dev/tty[A-Za-z]*')
elif sys.platform.startswith('darwin'):
ports = glob.glob('/dev/tty.*')
else:
raise EnvironmentError('Unsupported platform')
result = []
for port in ports:
try:
s = serial.Serial(port)
s.close()
result.append(port)
except (OSError, serial.SerialException):
pass
return result
if __name__ == '__main__':
print(serial_ports())
3 进行串口通讯：
def send_str(port, baudrate, parity, value):
port_set = serial.Serial(port=port, baudrate=baudrate, parity=parity)
port_set.write(value)
# delay 100ms if receive is blank, just waiting 5s.
n = 0
while port_set.inWaiting() == 0:
time.sleep(0.1)
n = n + 1
if n > 50:
# send frame again
port_set.write(value)
break
# every 100ms check the data receive is ready
byte_number_1 = 0
byte_number_2 = 1
while byte_number_1 != byte_number_2:
byte_number_1 = port_set.inWaiting()
time.sleep(0.1)
byte_number_2 = port_set.inWaiting()
receive_frame = port_set.read_all()
return receive_frame
port: 串口号，str格式，例如‘COM3’；
baudrate: 波特率，str格式，例如‘9600’；
parity:校验位，str格式。只需要第一个字母，‘N’无校验，‘O’奇校验，‘E’偶校验；
value: 设置的数据，数据需要为int格式，多字节传输采用list。
# delay 100ms if receive is blank, just waiting 5s.
n = 0
while port_set.inWaiting() == 0:
time.sleep(0.1)
n = n + 1
if n > 50:
# send frame again
port_set.write(value)
break
inWaiting()返回接收到的字符。
此段代码判断是否有数据返回。最多等待5s，之后重发。
# every 100ms check the data receive is ready
byte_number_1 = 0
byte_number_2 = 1
while byte_number_1 != byte_number_2:
byte_number_1 = port_set.inWaiting()
time.sleep(0.1)
byte_number_2 = port_set.inWaiting()
此段代码判断是否接收完成。每100ms判断一次，判断时间可以根据波特率进行修改。
receive_frame = port_set.read_all()
接收全部返回数据。返回数据类型为byte，可以采用与list相同方法进行操作。
4 判断端口是否可用
def serial_alive(port=None):
port_status = True
try:
s = serial.Serial(port)
s.close()
except OSError:
port_status = False
return port_status
if __name__ == '__main__':
print(serial_alive('COM5'))