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Pyserial example program error: win32file.SetupComm reports 'Incorrect function.'


I am using Python 2.5 on Windows XP. I have installed Pyserial and
win32all extensions.

When I try to run the example program scan.py (included below), or any
other program using pyserial, as soon as it hits the statement:

s = serial.Serial(i)

I get the error:

Traceback (most recent call last):
   File "C:\Python25\Doc\PySerial Examples\scan.py", line 26, in <module>
     for n,s in scan():
   File "C:\Python25\Doc\PySerial Examples\scan.py", line 17, in scan
     s = serial.Serial(i)
   File "C:\Python25\Lib\site-packages\serial\serialutil.py", line 156,
in __init__
     self.open()
   File "C:\Python25\lib\site-packages\serial\serialwin32.py", line 57,
in open
     win32file.SetupComm(self.hComPort, 4096, 4096)
error: (1, 'SetupComm', 'Incorrect function.')

What do I need to do to fix this? Thanks for the help!

   -- Ron

The example program scan.py (from the pyserial examples folder):
-----------------------------------------------
#!/usr/bin/env python
"""Scan for serial ports.
Part of pySerial (http://pyserial.sf.net)  (C)2002-2003 <cliec@gmx.net>

The scan function of this module tries to open each port number
from 0 to 255 and it builds a list of those ports where this was
successful.
"""

import serial

def scan():
     """scan for available ports. return a list of tuples (num, name)"""
     available = []
     for i in range(256):
         try:
             s = serial.Serial(i)
             available.append( (i, s.portstr))
             s.close()   #explicit close 'cause of delayed GC in java
         except serial.SerialException:
             pass
     return available

if __name__=='__main__':
     print "Found ports:"
     for n,s in scan():
         print "(%d) %s" % (n,s)

On Wed, 07 Feb 2007 11:14:39 -0800, Ron Jackson
<R@FascinatingElectronics.com> declaimed the following in
comp.lang.python:

> I am using Python 2.5 on Windows XP. I have installed Pyserial and
> win32all extensions.

        2.4 on XP Pro SP2...

> When I try to run the example program scan.py (included below), or any
> other program using pyserial, as soon as it hits the statement:

> s = serial.Serial(i)

>>> import serial
>>> for i in range(256):

...     try:
...             print i,
...             s = serial.Serial(i)
...             print s.portstr
...             s.close()
...     except serial.SerialException:
...             print
...            
0 COM1
1
2 COM3
3
4
5
6
7
8
9
10
11
and on and on...

> What do I need to do to fix this? Thanks for the help!

        Does the serial port module require a compile for use with 2.5?
Well, with only one download since Python 2.2, guess not...

        Something glitched in win32? Sorry, I don't know... However, since
those are Python source files, you could always plug in some debugging
lines around that win32 call to see what actually is there. Do you have
any unnatural serial ports on the machine? (Like a USB<>serial
converter?)

--
        Wulfraed        Dennis Lee Bieber               KD6MOG
        wlfr@ix.netcom.com              wulfr@bestiaria.com
                HTTP://wlfraed.home.netcom.com/
        (Bestiaria Support Staff:               web-a@bestiaria.com)
                HTTP://www.bestiaria.com/

Trying your program, I get the same error 'Incorrect function.':

Traceback (most recent call last):
   File "<pyshell#9>", line 4, in <module>
     s = serial.Serial(i)
   File "C:\Python25\Lib\site-packages\serial\serialutil.py", line 156, in __init__
     self.open()
   File "C:\Python25\lib\site-packages\serial\serialwin32.py", line 57, in open
     win32file.SetupComm(self.hComPort, 4096, 4096)
error: (1, 'SetupComm', 'Incorrect function.')

I tried PySerial on a laptop, also running XP Home SP2, and both the example
program and the program you suggested work fine on the laptop.

The desktop computer that is giving me the error doesn't have any unnatural
serial ports on it currently. The laptop worked fine, either with a USB device
emulating COMM6 present or with the USB device disconnected.

I checked and both machines are running the same version of win32file, which is
site-packages\win32\win32file.pyd, 88 KB dated 9/22/2006.

So my question is:

Why would the statement win32file.SetupComm(self.hComPort, 4096, 4096)

work just fine on one machine and not the other?

win32file.pyd can't be opened like a .py file, and I don't know what the rather
cryptic error 'Incorrect function.' is trying to tell me. Does anyone who is
familiar with win32file have an idea what the problem is?

Thanks for the help!

   -- Ron

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