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Groups > comp.lang.python > #24560
| From | Grant Edwards <invalid@invalid.invalid> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: PySerial could not open port COM4: [Error 5] Access is denied - please help |
| Date | 2012-06-27 23:24 +0000 |
| Organization | PANIX Public Access Internet and UNIX, NYC |
| Message-ID | <jsg4o8$o4p$1@reader1.panix.com> (permalink) |
| References | (10 earlier) <jsfv3v$imr$1@dont-email.me> <jsg05u$mgk$1@reader1.panix.com> <jsg0sj$4t9$1@reader1.panix.com> <ra2nu7h75720i75ijhabg12dngrab756e8@4ax.com> <jsg2pt$87s$1@dont-email.me> |
On 2012-06-27, Adam <adam@no_thanks.com> wrote:
>
>> Actually, I believe someone in an earlier thread in the newsgroup or
>> elsewhere pointed out that serial ports automatically open under
>> Windows. I'd have to look it back up when I have the time, which I
>> don't have at the moment, unfortunately.
What they're referring to is that on startup, Windows used to open
serial ports and query them to see if there was a serial mouse
connected. If it _thought_ it found a mouse, it would then hold the
port. I don't think that behavior has been enabled by default for a
long time.
If that were the case, then your terminal program wouldn't be able to
open the port either.
However, IIRC, some versions of windows do open and then close the
ports during the bus/device enumeration step of startup. However, they
don't keep the port open, so it doesn't affect the ability of user
applications to later open the port.
> Thanks, I think I read that as well but can't recall where.
>
> I am just running Python scripts (downloaded), which is not opening
> the serial port more than once (as Grant keeps assuming).
Well, I'm assuming your description of what you're doing is accurate.
If you're telling the truth, then the program is opening the port more
than once.
If the port wasn't already open, then calling ser.close() wouldn't do
_anything_. Here's the close() implmentation from pyserial:
def close(self):
"""Close port"""
if self._isOpen:
if self.hComPort:
# Restore original timeout values:
win32.SetCommTimeouts(self.hComPort, self._orgTimeouts)
# Close COM-Port:
win32.CloseHandle(self.hComPort)
win32.CloseHandle(self._overlappedRead.hEvent)
win32.CloseHandle(self._overlappedWrite.hEvent)
self.hComPort = None
self._isOpen = False
There's only _one_ place where self._isOpen is set to True, and that's
at the end of the open() call:
def open(self):
"""Open port with current settings. This may throw a SerialException
if the port cannot be opened."""
[...]
self._overlappedWrite.hEvent = win32.CreateEvent(None, 0, 0, None)
self._isOpen = True
If you have to add the call "ser.close()" before you can open the port
with "ser.open()", then that means that the port _was_already_open_.
--
Grant Edwards grant.b.edwards Yow! World War III?
at No thanks!
gmail.com
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PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-26 21:12 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help John Nagle <nagle@animats.com> - 2012-06-26 22:33 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-27 02:10 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Paul <nospam@needed.com> - 2012-06-27 08:28 -0400
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-27 08:26 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Paul <nospam@needed.com> - 2012-06-27 12:04 -0400
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-27 10:41 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Paul <nospam@needed.com> - 2012-06-27 14:04 -0400
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-27 13:40 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Grant Edwards <invalid@invalid.invalid> - 2012-06-27 21:18 +0000
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-27 14:48 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Grant Edwards <invalid@invalid.invalid> - 2012-06-27 22:06 +0000
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Grant Edwards <invalid@invalid.invalid> - 2012-06-27 22:18 +0000
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Temia Eszteri <lamialily@cleverpun.com> - 2012-06-27 15:31 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-27 15:51 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Grant Edwards <invalid@invalid.invalid> - 2012-06-27 23:24 +0000
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-27 17:14 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Grant Edwards <invalid@invalid.invalid> - 2012-06-28 14:15 +0000
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "Adam" <adam@no_thanks.com> - 2012-06-28 13:31 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Roel Schroeven <roel@roelschroeven.net> - 2012-06-28 21:08 +0200
Re: PySerial could not open port COM4: [Error 5] Access is denied- please help "Adam" <adam@no_thanks.com> - 2012-06-28 14:48 -0700
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help "David H. Lipman" <DLipman~nospam~@Verizon.Net> - 2012-06-27 08:28 -0400
Re: PySerial could not open port COM4: [Error 5] Access is denied - please help Grant Edwards <invalid@invalid.invalid> - 2012-06-27 14:53 +0000
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