python serial读串口

2023-01-31 03:28

短信预约 -IT技能 免费直播动态提醒

由于项目需求，需要从传感器节点和GPS中读取数据，所以学习了如何用python读串口。

python提供了pySerial，Linux和windows下有相应的模块

linux版本： pyserial (http://pyserial.wiki.sourceforge.net/pySerial) （在我的虚拟机中Ubuntu 12.04 LTS 版本中好像已经自带）

windows版本： pywin32 (http://sourceforge.net/projects/pywin32/) 下载直接安装

先看一个例子：

import serial
ser = serial.Serial('/dev/ttyTX0', 9600, timeout=1)
while True:
    data = ser.read(100)
    print repr(data)

1、读串口步骤：

实例化 --> 设置（当然可以一步完成）

2、serial详解

2.1 serial类原型

ser = serial.Serial(
port=None,              # number of device, numbering starts at
# zero. if everything fails, the user
# can specify a device string, note
# that this isn't portable anymore
# if no port is specified an unconfigured
# an closed serial port object is created
baudrate=9600,          # baud rate
bytesize=EIGHTBITS,     # number of databits
parity=PARITY_NONE,     # enable parity checking
stopbits=STOPBITS_ONE, # number of stopbits
timeout=None,           # set a timeout value, None for waiting forever

#zero, non-blocking mode, return immediately on read

xonxoff=0,              # enable software flow control
rtscts=0,               # enable RTS/CTS flow control
interCharTimeout=None   # Inter-character timeout, None to disable
)

注；Port可以用数字表示。COM1为 0，COM2为1 .......

也可以实用绝对路径：ser.port = '/dev/ttySAc2'

timeout说明（None和 0不同）：

timeout = None: 长时间等待

timeout = 0: 不阻塞形式 (读完之后就返回)

timeout = x: x秒后超时 (float allowed)

2.2 Serial方法：

open()                  # open port
close()                 # close port immediately
setBaudrate(baudrate)   # change baud rate on an open port
inWaiting()             # return the number of chars in the receive buffer
read(size=1)            # read "size" characters
write(s)                # write the string s to the port
flushInput()            # flush input buffer, discarding all it's contents
flushOutput()           # flush output buffer, abort output
sendBreak()             # send break condition
setRTS(level=1)         # set RTS line to specified logic level
setDTR(level=1)         # set DTR line to specified logic level
getCTS()                # return the state of the CTS line
getDSR()                # return the state of the DSR line
getRI()                 # return the state of the RI line
getCD()                 # return the state of the CD line

2.3 Serial 实例属性

portstr                 # device name
BAUDRATES               # list of valid baudrates
BYTESIZES               # list of valid byte sizes
PARITIES                # list of valid parities
STOPBITS                # list of valid stop bit widths

以下属性可以改变，即使在端口打开时也可以重新赋值

port                    # port name/number as set by the user
baudrate                # current baud rate setting
bytesize                # byte size in bits
parity                  # parity setting
stopbits                # stop bit with (1,2)
timeout                 # timeout setting
xonxoff                 # if Xon/Xoff flow control is enabled
rtscts                  # if hardware flow control is enabled

3.简单实例

import serial
ser = serial.Serial()
def hexShow(argv):
    result = ''
    hLen = len(argv)
    for i in xrange(hLen):
        hvol = ord(argv[i])
        hhex = '%02x'%hvol
        result += hhex+' '
        print 'hexShow:',result
ser.baudrate = 57600
ser.port = '/dev/ttySAC2'

ser.open()
readstr = ser.read(20)
print ser.portstr
hexShow(readstr)

执行结果如图：