code: function hex2a(hex) {
    var str = '';
    if (hex){
      var hexstr = hex.toString('ascii');//force conversion
      for (var i = 0; i < hexstr.length; i += 2) {
          //we will display only readable chars
          var intChar = parseInt(hexstr.substr(i,2),16);
          if ((intChar > 31) & (intChar < 127)) {
            str += String.fromCharCode(intChar);
          }
          else {
            str += " ";
          }
      }
    }
    return str;
  }
docs: display only readable chars (ascii 31-127)