Node.JS中未处理的“错误”事件

Question

I'm trying to active an RFID reader through node.js and then send the tag back.

It works great. It reads the tag, responds with an ID, then send the ID to the pinging node client.

However, every time the node.JS program picks up a set of data from an RFID tag, after it sends, it closes down with the following error:

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: EBADF, read

This causes the node process to quit all the time. What could be the problem here?

My code is the following;

// Socket.io server details
var io = require('socket.io').listen(3000);
// Serialport plugin declared and made a serialport variable
var serialport = require("serialport");
var SerialPort = serialport.SerialPort;
// Variable containing technical USB port details
var serialPort = new SerialPort("/dev/ttyUSB0", 
 {baudrate: 2400, parser: serialport.parsers.readline("\n")},
 false); // this is the openImmediately flag [default is true]



io.sockets.on('connection', function (socket) {

 console.log('user connected');

 socket.on('ping', function (data) {

 serialPort.open(function () {

 // Open notification
 console.log('open');

 //Start listening
 serialPort.on('data', function(data) {


 // If content is empty, filter out
 if (data.trim() !== '') {
 line = data;

 //Execute function again, get tag, handle tag and end process
 serialPort.close(function () {
 console.log('De uiteindelijke tag is ' + data);
 console.log('Ping received with data: ' + data);
 socket.emit('pong', data);
 console.log('closing');
 });
 console.log('hallo');
 }
 });
 });


 });
});

Answer 1

Add a listener to handle the error in the serial port, like the code below:

serialPort.on('error', function(error) {
   console.log('The error: '+error);
   //...
});