Hi everyone,

 I am using Mission Planner for a project. I need to get the altitude data out of the Mission Planner software via serial communication. To do so, I have tried to use a python script.  

 In my understanding from what I have read on the website 

http://planner.ardupilot.com/wiki/using-python-scripts-in-mission-planner/

 to add standard python libraries, I needed to add a line like 

sys.path.append(r"c:\python27\lib")to my code. I did that as well. But when I run the script in Mission Planner, I get an error, saying that
"Error running script Port is already open" 
OR there is another error if I try to establish serial connection to Arduino Mega board from Mission Planner
"Error running script Access to the Port 'COM1' is denied"
How can I overcome this problem, what might be the reason for it? 
You can my veery simple python script here as well.

#!/usr/bin/python

import sys
sys.path.append(r"c:\python27\lib")
sys.path.append(r"c:\Python27\Lib\pyserial-2.7")
import serial

print 'I am connected to Mission Planner!!!'

print 'I am alive!!!'

print cs.alt

print cs.pitch

ser = serial.Serial('COM1', 57600, timeout=10)
ser.open()
ser.write(float(cs.alt))

 Thank you all in advance for all the help!