Async read & write with serialport communcatio

var callbackStack = [];

const parser = port.pipe(new ByteLength({length: 11}))
parser.on('data', function (data) {
  if (callbackStack.length > 0) {
    var callback = callbackStack.pop();

    callback(null, data);
  };
  console.log('DATA RECEIVED: ', Buffer.from(data, 'hex'))
});

function sendToPort (data, callback) {
  port.write(data, function (err, res) {
    if (err) {
      callbackStack.splice(callbackStack.indexOf(callback), 1);
      callback(err);
    };
    console.log('DATA WRITTEN: ', data)
  });
  callbackStack.unshift(callback);
};

function bl(cb){
    var async  = require("async");
    var hex = ['aa5501020304050607080a', 'aa5501020304050607080a', 'aa5501020304050607080a'];
    port.open(function(err){
        var i = 0;
        async.eachSeries(hex, function(item,next){
            var buf = Buffer.from(item, 'hex');
            sendToPort (buf, function(err,data){
              var buf1 = Buffer.from(data, 'hex');
              var buf2 = Buffer.from('aa5501020304050607080a', 'hex');
              var x = Buffer.compare(buf1, buf2);

              if(x === 0) next();


            });
        i++
        },function(err){
          console.log('ERROR:', err);
        });
    });
}
bl();