serialport.js

var SerialPort      = require( 'serialport' );
var debug = require('debug')('foo');
  var uartPath        = "/dev/ttyO1";
  var uartBaud        = 115200;
  var serialConnected =false;

    serialPort = new SerialPort.SerialPort( uartPath,
    {
      baudrate: 115200,
        lock:true,
parity:'none',
dataBits: 8,
stopBits: 1,
      parser: SerialPort.parsers.readline('\r','utf8')
//      parser: SerialPort.parsers.readline( '\r\n' )
    } );


    serialPort.on( 'open', function()
    {
      serialConnected = true;
      debug('@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@');
    } );

    serialPort.on( 'close', function( data )
    {
      console.log( 'Serial port closed!' );
      serialConnected = false;
    } );

    serialPort.on( 'data', function( data )
    {
      debug('data: ' + data.toString());
    } );

Data from a readline parser is already a string