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socket.io-serialport

socket.io-serialport

Expose a serial port over a socket.io instance. Particular thanks go to the serialport, socket.io-stream and hterm projects.

Usage

npm install --save socket.io
npm install --save socket.io-serialport

Then to connect to a serial port and open it (note that the options field is passed directly to the serialport instance, however the autoOpen option will always be forced to false)

const Server = require('socket.io');
const SerialPort = require('socket.io-serialport');
 
const io = new Server(8080);
 
const serialport = new SerialPort({
  io: io,
  route: '/port/ttyS0',
  captureFile: '/var/log/serialport/ttyS0',
  retryPeriod: 1000,
  device: '/dev/ttyS0',
  options: {
    baudrate: 115200
  }
});
 
serialport.open()
.then(() => {
  console.log('port opened');
 
  // And when done (shutting down, etc) 
  serialport.close()
  .then(() => {
    console.log('port closed');
  });
});

Then connect socket.io clients to the following endpoint

var io = require('socket.io-client');
 
var ttyS0 = io('http://localhost:8080/port/ttyS0');

with the socket.io instance you can just use data events

// listen for data from the serial port 
ttyS0.on('data', function(data) {
  console.log(data);
});
 
// Send some data to the serial port 
ttyS0.emit('data', 'pwd\n');

Or connect socket.io-stream clients to use streams

// Create a duplex stream 
var ttyS0Stream = ss.createStream();
 
// listen for data from the serial port 
ttyS0Stream.on('data', function(data) {
  console.log(data);
});
 
// Notify the server with a `stream` event to setup 
// a duplex stream at the other end which will 
// pipe to and from the serial port 
ss(ttyS0).emit('stream', ttyS0Stream);
 
// Send some data to the serial port 
ttyS0Stream.write('pwd\n');

or both :)

Handling serial port disconnects, etc

Events will be emitted when the state of the remote serial port changes. You can use these events to notify a user, etc.

Also on initial connection of the socket an event should be received giving the current status of the port.

ttyS0.on('status', function(status) {
  console.log(status);
});

where status will be one of

  • {status: 'open'} - the port is open
  • {status: 'closing'} - the port is closing after calling #close
  • {status: 'closed'} - the port is closed after calling #close
  • {status: 'disconnected', error: error} - the port disconnected and should be reopened after the retryPeriod
  • {status: 'opening', error: error} - the port is opening, the error field will be set if it is reopening after an error