Arduino-pyFirmata-Python windows error(5,access denied)

Question

Good Morning

I want to connect my Arduino board to the pc using pyFirmata lib but a strange problem has occured. Premise: pySerial and pyFirmata are succesfully installed on my computer. I have windows 8.0 64 bit. The drivers of the Arduino and the USB ports are working fine (since I can upload every sketch to Arduino).

The code I want run is very simple:

If a button (connected to the pin 4, configured as an input by the method.get_pin() from firmata library) is pushed a red led will blink, otherwise a green led will do. I make them blink with an easy function:

from time import sleep
def Blink(pin):
    board.digital(pin).write(1)
    sleep(1)
    board.digital(pin).write(0)
    sleep(1)

board is defined in the global scope as pyfirmata.Arduino('com3')

All contact works fine since i have test them with firmata_test.exe and I'm sure that none serial connections are open before I start python.

Here the strange thing:

If I write every command on the python shell the whole thing works fine, leds blink right!! BUT if I write all commands on a module and then I run it it gives out this error:

"Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    board = pyfirmata.Arduino('com3')
  File "C:\Python27\lib\site-packages\pyfirmata\__init__.py", line 16, in __init__
    super(Arduino, self).__init__(*args, **kwargs)
  File "C:\Python27\lib\site-packages\pyfirmata\pyfirmata.py", line 89, in __init__
    self.sp = serial.Serial(port, baudrate, timeout=timeout)
  File "C:\Python27\lib\site-packages\serial\serialwin32.py", line 38, in __init__
    SerialBase.__init__(self, *args, **kwargs)
  File "C:\Python27\lib\site-packages\serial\serialutil.py", line 282, in __init__
    self.open()
  File "C:\Python27\lib\site-packages\serial\serialwin32.py", line 66, in open
    raise SerialException("could not open port %r: %r" % (self.portstr, ctypes.WinError()))
SerialException: could not open port 'com3': WindowsError(5, 'Access denied.')"

That is, it cannot open the port. I have tried some debugging but it didn't help me.

If I check the status of the port by

por = serial.Serial()
    por.port = 'com3'
    por.isOpen()
>>False

BUT if i use

por = serial.Serial('com3')

it pops up the same error.

Looking Arduino the TX led blink regularly so I can imagine that it is sending some data to the serial port. If I open arduino app it tells me that the port is busy. I can't fiure out if it is a problem of administrator permits, because I run py IDLE as admin. Even if I run the script from CMD in admin mode the error remains.

Thank you very much for every answer.

Answer 1

Guys I solved the problem! I rebooted the pc then (FIRST OF ALL) I started CMD in admin mode and ran the module.. Now it Works! Don't know why, it seems that until now I was running the first time without admin permissions. After that even though I open CMD in admin mode the error continued to appear.

Hope this can be helpful to someone.

Thank you.