Custom parser for node-serialport? - node.js

Question

With incomming data like STX(0x02)..Data..ETX(0x03)
I can process data by byte sequence parser:
var SerialPort = require('serialport');
var port = new SerialPort('/dev/tty-usbserial1', {
parser: SerialPort.parsers.byteDelimiter([3])
});
port.on('data', function (data) {
console.log('Data: ' + data);
});
But my actual incomming data is STX(0x02)..Data..ETX(0x03)..XX(plus 2 characters to validate data)
How can I get appropriate data?
Thanks!

Answer 1

Since version 2 or 3 of node-serialport, parsers have to inherit the Stream.Tansform class. In your example, that would become a new class.
Create a file called CustomParser.js :
class CustomParser extends Transform {
constructor() {
super();
this.incommingData = Buffer.alloc(0);
}
_transform(chunk, encoding, cb) {
// chunk is the incoming buffer here
this.incommingData = Buffer.concat([this.incommingData, chunk]);
if (this.incommingData.length > 3 && this.incommingData[this.incommingData.length - 3] == 3) {
this.push(this.incommingData); // this replaces emitter.emit("data", incomingData);
this.incommingData = Buffer.alloc(0);
}
cb();
}
_flush(cb) {
this.push(this.incommingData);
this.incommingData = Buffer.alloc(0);
cb();
}
}
module.exports = CustomParser;
Them use your parser like this:
var SerialPort = require('serialport');
var CustomParser = require('./CustomParser ');
var port = new SerialPort('COM1');
var customParser = new CustomParser();
port.pipe(customParser);
customParser.on('data', function(data) {
console.log(data);
});

Answer 2

Solved!
I write my own parser:
var SerialPort = require('serialport');
var incommingData = new Buffer(0);
var myParser = function(emitter, buffer) {
incommingData = Buffer.concat([incommingData, buffer]);
if (incommingData.length > 3 && incommingData[incommingData.length - 3] == 3) {
emitter.emit("data", incommingData);
incommingData = new Buffer(0);
}
};
var port = new SerialPort('COM1', {parser: myParser});
port.on('data', function(data) {
console.log(data);
});