PySerial could not open port COM4: [Error 5] Access is denied - please help

[David H. Lipman]

From: "Adam" <adam at no_thanks.com>

>
> "John Nagle" <nagle at animats.com> wrote in message 
> news:jse604$1cq$1 at dont-email.me...
>> On 6/26/2012 9:12 PM, Adam wrote:
>>> Host OS:    Ubuntu 10.04 LTS
>>> Guest OS:    Windows XP Pro SP3
>>>
>>> I am able to open port COM4 with Terminal emulator.
>>>
>>> So, what can cause PySerial to generate the following error ...
>>>
>>> C:\Wattcher>python wattcher.py
>>> Traceback (most recent call last):
>>>    File "wattcher.py", line 56, in <module>
>>>      ser.open()
>>>    File "C:\Python25\Lib\site-packages\serial\serialwin32.py", line 56, 
>>> in
>>> open
>>>      raise SerialException("could not open port %s: %s" % (self.portstr,
>>> ctypes.WinError()))
>>> serial.serialutil.SerialException: could not open port COM4: [Error 5]
>>> Access is denied.
>>
>>     Are you trying to access serial ports from a virtual machine?
>> Which virtual machine environment?  Xen?  VMware? QEmu?  VirtualBox?
>> I wouldn't expect that to work in most of those.
>>
>>     What is "COM4", anyway?   Few machines today actually have four
>> serial ports.  Is some device emulating a serial port?
>>
>> John Nagle
>>
> Thanks, and yes, I am using VirtualBox.  My laptop does not have a serial 
> port so
> I use a USB-to-serial converter, which is assigned COM4.
>

Then it is a Virtual COM port.  Often software will want to communicate 
directly to the COM4 port which is usually at: IRQ3 and I/O 2E8h.

-- 
Dave
Multi-AV Scanning Tool - http://multi-av.thespykiller.co.uk
http://www.pctipp.ch/downloads/dl/35905.asp