Imprimindo com Bematech MP-4200 com node.js (sem cups nem módulos nativos)

bematech.js

var fs = require('fs');

String.prototype.toBytes = function() {
    var arr = []
    for (var i=0; i < this.length; i++) {
        arr.push(this[i].charCodeAt(0))
    }

    return arr;
}

var printData = "Hello World!".toBytes().concat([0x01B, 0x64, 10, 0x1d, 0x56, 0x00]);

var wstream = fs.createWriteStream('/dev/ttyACM0', { 
  encoding: 'utf16le' 
});

wstream.write(new Buffer(printData));
wstream.end();