Arduino Python Serial

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1

Hi,

I see your post in Arduino Forum.

I want to get data from serial port, so I used this code to arduino:

int potPin = 0;

void setup()
{
Serial.begin(9600);
}

void loop()
{
int val = map(analogRead(potPin), 0, 1023, 0, 255);
Serial.println(val);
delay(1000);
}

And this code to python:

import serial
ser=serial.Serial(port='COM3',timeout=3)
s=ser.read(100) #reading up to 100 bytes
print s

When I connect the arduino to the serial port, python show 4 values from the serial port. But, if a run the code in python again, occurs this error:

raise SerialException("could not open port %s: %s" % (self.portstr, ctypes.WinError()))
serial.serialutil.SerialException: could not open port COM3: [Error 5] Access denied.

Can you help me?

Thanks

2

does the python script release the com port ? ==> you might need an explicit ser.close()

be aware that ser.read(100) read 100 bytes and that the Arduino sends 1-4 chars followed by \r\n per value.
So the variable s need to be processed to get the values back.