CODEWITHSUNDEEP
htmlnode.jstcpsocket.iosensors
Chintan Pathak
Chintan Pathak

Reputation: 301

How to get sensor data over TCP/IP in nodejs?

I have a nodejs app with socket.io. To test this, save the below listing as app.js. Install node, then npm install socket.io and finally run on command prompt: node app.js

var http = require('http'),
fs = require('fs'),
// NEVER use a Sync function except at start-up!
index = fs.readFileSync(__dirname + '/index.html');

// Send index.html to all requests
var app = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.end(index);
});

// Socket.io server listens to our app
var io = require('socket.io').listen(app);

// Send current time to all connected clients
function sendTime() {
    io.sockets.emit('time', { time: new Date().toJSON() });
}

// Send current time every 10 secs
setInterval(sendTime, 5000);

// Emit welcome message on connection
io.sockets.on('connection', function(socket) {
    socket.emit('welcome', { message: 'Welcome!' });

    socket.on('i am client', console.log);
});

app.listen(3000);

This code sends data to the file index.html. After running the app.js, open this file in your browser. 

<!doctype html>
<html>
    <head>
        <script src='http://code.jquery.com/jquery-1.7.2.min.js'></script>
        <script src='http://localhost:3000/socket.io/socket.io.js'></script>
        <script>
            var socket = io.connect('//localhost:3000');

            socket.on('welcome', function(data) {
                $('#messages').html(data.message);

                socket.emit('i am client', {data: 'foo!'});
            });
            socket.on('time', function(data) {
                console.log(data);
                $('#messages').html(data.time);
            });
            socket.on('error', function() { console.error(arguments) });
            socket.on('message', function() { console.log(arguments) });
        </script>
    </head>
    <body>
        <p id='messages'></p>
    </body>
</html>

The data sent right now is the current time and index.html works fine, updates the time every five seconds.

I want to modify the code so that, it reads my sensor data over TCP. My sensors are connected thru a data acquisition system and relays the sensor data over IP: 172.16.103.32 port:7700. (This is over LAN, so will not the accessible to you.)

How can this be implemented in nodejs?

Is SensorMonkey a viable alternative ? If so, any pointers on how to go about using it?

Upvotes: 2

Views: 15958

Answers (1)

Chintan Pathak
Chintan Pathak

Reputation: 301

I have a decent hack that is working right now, for which I request the readers to comment on....

var net = require('net'),
http = require('http'),
port = 7700,                    // Datalogger port
host = '172.16.103.32',         // Datalogger IP address
fs = require('fs'),
// NEVER use a Sync function except at start-up!
index = fs.readFileSync(__dirname + '/index.html');

// Send index.html to all requests
var app = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.end(index);
});

// Socket.io server listens to our app
var io = require('socket.io').listen(app);

// Emit welcome message on connection
io.sockets.on('connection', function(socket) {
    socket.emit('welcome', { message: 'Welcome!' });

    socket.on('i am client', console.log);
});

//Create a TCP socket to read data from datalogger
var socket = net.createConnection(port, host);

socket.on('error', function(error) {
  console.log("Error Connecting");
});

socket.on('connect', function(connect) {

  console.log('connection established');

  socket.setEncoding('ascii');

});

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

  console.log('DATA ' + socket.remoteAddress + ': ' + data);
  io.sockets.emit('livedata', { livedata: data });        //This is where data is being sent to html file 

});

socket.on('end', function() {
  console.log('socket closing...');
});

app.listen(3000);

References:

  1. Socket.io Website - www.socket.io - Its the buzzword now.
  2. TCP Socket Programming
  3. Nodejs "net" module
  4. Simplest possible socket.io example.

Upvotes: 1

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