mkpacket.js

var SerialPort = require('serialport');
// /dev/tty.usbserial-FTZ2C9FV
var port = new SerialPort(process.argv[2], {
  baudRate: 1200
}, function (err) {
  if (err) {
    return console.log('Error: ', err.message);
  }
  port.on('data', function (data) {
    console.log('Data: ' + data.toString('hex') );
  });
});

package.json

{
  "name": "dump-smartev-data",
  "version": "1.0.0",
  "dependencies": {
    "serialport": "^4.0.1"
  }
}