Arduino Serial data communication with NodeJS

Question

I am using an Arduino Uno and a DTH11 temperature sensor to read temperature and then send that value to a computer via the serial port.

A NodeJS application is running on the computer and captures that value and writes to a log file.

When I try to get values from my NodeJS application, sometimes the value is broken into two values. Eg: 25 -> 2 and 5

This is my Arduino code:

dht DHT;

#define DHT11_PIN 7
float tem [4];

void setup() {
  Serial.begin(9600);
  pinMode(12, OUTPUT); 
}

void loop() {
  int chk = DHT.read11(DHT11_PIN);
  int val = (int)(DHT.temperature);
  Serial.println(val);
  delay(600000);
}

This is my NodeJS program.

var fs = require('fs')
var logger = fs.createWriteStream('/data/Temperature/temperature.csv', {
  flags: 'a' // 'a' means appending (old data will be preserved)
})

var SerialPort = require("serialport")
var serialPort = new SerialPort("/dev/ttyACM0", {
  baudRate: 9600,
});

serialPort.on("open", function () {
  serialPort.on('data', function(data) {
    var moment = require('moment');
    var dayTime = moment().format('YYYY-MM-DD,hh:mm');
    var val1 = data.toString();
    var val = val1.trim();
    if (val == '') {
      console.log('no data');
    else {
      console.log(val);
      logger.write(dayTime + ',' + val + '\n');
    }
  });
});

Is it a problem with my code?

Thanks in advance.

Answer 1

As Look Alterno wrote in a comment, you need to parse the incoming data on the receiving side. In this instance, you have to look for the line terminators. The Node.js serialport module provides a parser for this called Readline. Read that doc and use it.