python serial读串口

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：