Sending serial data with python gives an error on windows but not on linux

Question

I'm using python to send data out to my arduino and for some reason under windows it's giving me an error. Below is my code.

import serial 

ser = serial.Serial("COM3")

ser.write('1')

Here is the error.

  File "C:\Python25\lib\site-packages\serial\serialwin32.py",
line 255, in write raise SerialException("WriteFile failed (%s)" % ctypes.WinError()) serial.serialutil.SerialException: WriteFile failed ([Error 9] The handle is invalid.)

Any idea why it's giving me this?

Use the 101010 button for proper code formatting.

Chris Morgan
– Chris Morgan

2010-11-22 04:23:21 +00:00
Commented Nov 22, 2010 at 4:23 — Chris Morgan
– Chris Morgan, Commented Nov 22, 2010 at 4:23

Eli Bendersky · Accepted Answer · 2010-11-22 04:29:03Z

1

Are you sure COM3 is a valid serial port on your Windows box? Can you open it with HyperTerminal and send stuff to it?

If it is, another thing to try is to replace it with the fully qualified name, for example:

port = "\\\\.\\COM3"
ser = serial.Serial(port, 38400)

answered Nov 22, 2010 at 4:29

Eli Bendersky

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1 Comment

detly Over a year ago

Yet another thing to do is replace "COM3" with the literal int 2.

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