Issues with Python readline() when reading data from Arduino

Question

I am attempting to use pyserial to read the data from an arduino on Windows.

import serial

device      = 'COM3'
baud        = 9600

with serial.Serial(device,baud, timeout = 0) as serialPort:
    while True:
        line = serialPort.readline()
        line = line.decode("utf-8")
        if line:
            print(line)

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

void loop() {

  int x = 12;
  int y = 34;
  int z = 56;
  Serial.print(x);
  Serial.print(',');
  Serial.print(y);
  Serial.print(',');
  Serial.println(z);  

}

The arduino Serial monitor is outputting exactly what I expect.

12,34,56
12,34,56
12,34,56

The python script on the other hand is outputting:

I have tried delaying the output from the Arduino, I have tried making a buffer in the arduino code and only output the data when the buffer was full, thinking maybe python would have time to read it correctly.

I have see numerous people on this site and others make similar code and suggest it works fine, I however cannot get coherent data from python. Anyone know my issue?

Viewed · Accepted Answer · 2020-06-07 12:39:48Z

1

Try to do like this

Python

import serial

device = 'COM3'
baud = 9600

with serial.Serial(device, baud) as port:
    while True:
        print(port.readline().decode("utf-8"))

Arduino

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

void loop() {
  int x = 12;
  int y = 34;
  int z = 56;
  Serial.println(x + ',' + y + ',' + z);  
}

answered Jun 7, 2020 at 12:39

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1 Comment

Colin Runnion Over a year ago

Fixed! Thank you! The python code and arduino code work together from this comment, however, my original python script works as well as an FYI.

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