转：Python通过pyserial控制串口操作
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https://blog.csdn.net/lovelyaiq/article/details/48101487
你想通过串行端口读写数据,典型场景就是和一些硬件设备打交道(比如一个机器人或传感器)。尽管你可以通过使用Python内置的I/O模块来完成这个任务,但对于串行通信最好的选择是使用 pySerial包 。 这个包的使用非常简单,先安装pySerial,使用类似下面这样的代码就能很容易的打开一个串行端口:
一、用python操作串口，首先需要下载相关模块:
pyserial (http://pyserial.wiki.sourceforge.net/pySerial)
pywin32 (http://sourceforge.net/projects/pywin32/)
import serial
ser = serial . Serial(‘/dev/tty.usbmodem641‘, # Device name varies
baudrate = 9600,
bytesize = 8,
parity = ‘N‘,
stopbits = 1)
设备名对于不同的设备和操作系统是不一样的。 比如,在Windows系统上,你可以使用0,1等表示的一个设备来打开通信端”COM0”和”COM1”。 一旦端口打开,那就可以使用read() , readline() 和 write() 函数读写数据了。
二,十六进制显示
十六进制显示的实质是把接收到的字符转换成其对应的ASCII码，然后将ASCII码值再转换成十六进制数显示出来，这样就可以显示特殊字符了。在这里定义了一个函数，如hexShow(argv)，代码如下：
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import 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
t = serial.Serial(‘com12‘,9600)
print t.portstr
strInput = raw_input(‘enter some words:‘)
n = t.write(strInput)
print n
str = t.read(n)
print str
hexShow(str)
3,十六进制发送
十六进制发送实质是发送十六进制格式的字符串，如‘xaa‘，‘x0b‘。重点在于怎么样把一个字符串转换成十六进制的格式，有两个误区：
1）‘x‘+‘aa‘是不可以，涉及到转义符反斜杠
2）‘\x‘+‘aa‘和r‘x‘+‘aa‘也不可以，这样的打印结果虽然是xaa，但赋给变量的值却是‘\xaa‘
这里用到decode函数，
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list=‘aabbccddee‘
hexer=list.decode("hex")
print hexer
需要注意一点，如果字符串list的长度为奇数，则decode会报错，可以按照实际情况，用字符串的切片操作，在字符串的开头或结尾加一个‘0‘
假如在串口助手以十六进制发送字符串"abc"，那么你在python中则这样操作“self.l_serial.write(”x61x62x63") ”
当然，还有另外一个方法：
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strSerial = "abc"
strHex = binascii.b2a_hex(strSerial)
#print strHex
strhex = strHex.decode("hex")
#print strhex
self.l_serial.write(strhex);
Short introduction
Open port 0 at "9600,8,N,1", no timeout
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>>> import serial
>>> ser = serial.Serial(0) # open first serial port
>>> print ser.portstr # check which port was really used
>>> ser.write("hello") # write a string
>>> ser.close() # close port
Open named port at "19200,8,N,1", 1s timeout
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>>> ser = serial.Serial(‘/dev/ttyS1‘, 19200, timeout=1)
>>> x = ser.read() # read one byte
>>> s = ser.read(10) # read up to ten bytes (timeout)
>>> line = ser.readline() # read a ‘
‘ terminated line
>>> ser.close()
Open second port at "38400,8,E,1", non blocking HW handshaking
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>>> ser = serial.Serial(1, 38400, timeout=0,
... parity=serial.PARITY_EVEN, rtscts=1)
>>> s = ser.read(100) # read up to one hundred bytes
... # or as much is in the buffer
Get a Serial instance and configure/open it later
>>> ser = serial.Serial()
>>> ser.baudrate = 19200
>>> ser.port = 0
>>> ser
Serial<id=0xa81c10, open=False>(port=‘COM1‘, baudrate=19200, bytesize=8, parity=‘N‘, stopbits=1, timeout=None, xonxoff=0, rtscts=0)
>>> ser.open()
>>> ser.isOpen()
True
>>> ser.close()
>>> ser.isOpen()
False
Parameters for the Serial class
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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
xonxoff=0, # enable software flow control
rtscts=0, # enable RTS/CTS flow control
interCharTimeout=None # Inter-character timeout, None to disable
)
The port is immediately opened on object creation, if a port is given. It is not opened if port is None.
Options for read timeout:
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timeout=None # wait forever
timeout=0 # non-blocking mode (return immediately on read)
timeout=x # set timeout to x seconds (float allowed)
Methods of Serial instances
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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
Attributes of Serial instances
Read Only:
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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
New values can be assigned to the following attributes, the port will be reconfigured, even if it‘s opened at that time:
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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
Exceptions
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serial.SerialException
Constants
parity:
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serial.PARITY_NONE
serial.PARITY_EVEN
serial.PARITY_ODD
stopbits:
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serial.STOPBITS_ONE
al.STOPBITS_TWO
bytesize:
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serial.FIVEBITS
serial.SIXBITS
serial.SEVENBITS
serial.EIGHTBITS
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作者：TiRan_Yang
来源：CSDN
原文：https://blog.csdn.net/lovelyaiq/article/details/48101487
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