title: Trying to open a serial port with pyserial on WinXP -> "Access denied"
body: <p>I'm trying to send data to an hplc pump via the serial port using python and pyserial. I tested the cable and the pump under linux (a gentoo derivative), where it worked perfectly, albeit as root. Now i have to use the code on a WinXP machine, where i always get an "Access denied" error when trying to open the port (i adjusted the parameters to COMxx instead of ttySxx, the port is found). 
  I tried the serial port of the computer, as well as a USB2Serial adapter.
  I heard that WinXP was quite restrictive when it comes to trying to address some port with self written code. 
  Is there a simpler workaround for this problem than installing linux?</p>
  
  <pre><code># -*- coding: utf-8 -*-
  
  import sys
  import time
  import serial
  from threading import Thread
  
  """
  usage: cmdCapture workDirectory pictureTime pressureTime
  """
  
  print 'successful import is successful'
  
  workDir=sys.argv[1]
  pressureThresh=float(sys.argv[3])
  
  class doCapture(Thread):
  def __init__ (self, workDir, pressureThresh):
      Thread.__init__(self)
  
      self.workDir=workDir
      self.pressureThresh=pressureThresh
      self.pressureTimer=0
  </code></pre>
  
  <h1>-> here i set the serial port</h1>
  
  <pre><code>    self.ser=serial.Serial(port='\\.\COM1', baudrate=9600, bytesize=serial.EIGHTBITS, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=1)
  </code></pre>
  
  <h1>-> here the error happens</h1>
  
  <pre><code>    self.ser.open()
  
  def getPressure(self):
      self.ser.write('PR')
      return self.ser.read(size=8), timer.timer()
  
  def run(self):
      self.pressureTimer=time.timer()
      while 1:
          if self.pressureTimer&lt;=(time.timer()-self.pressureTime):
              self.p=getPressure()
              print self.p
  
  myCapture=doCapture(workDir, pressureThresh)
  myCapture.start()
  </code></pre>