[Tutor] Serial communication ...

[Emile van Sebille]

On 9/13/2010 8:36 AM Markus Hubig said...
> Hi @all!
>
> I'm about to write a class for serial communication on Win32 and Linux which
> provides a method called "talk" to send something over the serial line,
> wait for
> the answer and returns it. My problem is, that I don't know how long the
> answer
> will be (ok max 260 bytes but most answers are much smaller).
>
> This is what I have now, please leave some comments:
>
>     1. Will this work on Win32 (with select)?
>     2. Should I better use twisted.internet.serialport?
>     3. Will self.read(260)block until it reads the full 260 bytes?
>

You're subclassing Serial -- the answers to your questions depend on 
what that is.  So, what is it? Does it support windows? Has anyone 
compared/contrasted it to twisted.internet.serialport?  What does its 
read do?  And finally, perhaps, does it have it's own support 
group/list?  You'll probably get better answers directly from there than 
here.

HTH,

Emile




> class SerialDevice(Serial):
>
>      def __init__(self,port):
>          Serial.__init__(self)
>          self.port = port
>          self.baudrate = 57600
>          self.bytesize = EIGHTBITS
>          self.parity = PARITY_ODD
>          self.stopbits = STOPBITS_TWO
>          self.timeout = 0
>          self.xonxoff = 0
>          self.rtscts = 0
>          self.dsrdtr = 0
>          self.open()
>          self.flush()
>
>      def _write(self, packet):
>          fileno = self.fileno()
>          while True:
>              readable, writeable, excepts = select( [], [fileno], [], 0.2 )
>              if fileno in writeable:
>                  time.sleep(0.1)
>                  length = self.write(packet)
>                  break
>          return length
>
>      def _read(self):
>          fileno = self.fileno()
>          while True:
>              readable, writeable, excepts = select( [], [fileno], [], 0.2 )
>              if fileno in readable:
>                  time.sleep(0.1)
>                  packet = self.read(260)
>                  break
>          return packet
>
>      def talk(self, packet):
>          self._write(packet)
>          responce = self._read()
>          return responce
>
> Thank you, Markus
>
>
>
>
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