xbee-api cannot lock port

[fxsh1301]

感謝使用 Node.js Taiwan AMA，以下附上簡單提問範例供參考，請把內容改成你自己遇到的問題

目的

在xbeeapi.on接收封包的同時
能夠週期性的發送另外的封包

使用的工具

在Pi3上安裝node.js v6.9.5
透過tx/rx連結xbee coordinator

操作流程

xbeeApi.on負責接收封包並根據來源節點地址回送ack及資訊
但想要再加入另外週期發送封包的動作

遇到的問題

若放入xbeeApi.on中需待有資料進入才會執行該段動作
在外部的話則是會有port被lock住的問題

嘗試過的解法

同上

程式碼

var util = require('util');
var SerialPort = require('serialport');
var xbee_api = require('xbee-api');

var C = xbee_api.constants;

var xbeeAPI = new xbee_api.XBeeAPI({
api_mode: 2
});

var serialport = new SerialPort("/dev/ttyS0", {
baudrate: 9600,
parser: xbeeAPI.rawParser()
});

var d= new Date();
var yyyy =d.getFullYear()
var MM = (d.getMonth()+1<10 ? '0' : '')+(d.getMonth()+1);
var dd = (d.getDate()<10 ? '0' : '')+d.getDate();
var h = (d.getHours()<10 ? '0' : '')+d.getHours();
var m = (d.getMinutes()<10 ? '0' : '')+d.getMinutes();
var s = (d.getSeconds()<10 ? '0' : '')+d.getSeconds();

/*
var frame_obj_ack = {
type: 0x10,
id: 0x01,
destination64: "0013a20040d8da93" ,
broadcastRadius: 0x00,
options: 0x00,
// data: ""+h+m+s+dd+MM+yyyy
data:"hi"
};

serialport.on("open", function () {
serialport.write(xbeeAPI.buildFrame(frame_obj_ack));
console.log('Sent to serial port.');
});
*/

// All frames parsed by the XBee will be emitted here
xbeeAPI.on("frame_object", function (frame) {
var d= new Date();
var yyyy =d.getFullYear()
var MM = (d.getMonth()+1<10 ? '0' : '')+(d.getMonth()+1);
var dd = (d.getDate()<10 ? '0' : '')+d.getDate();
var h = (d.getHours()<10 ? '0' : '')+d.getHours();
var m = (d.getMinutes()<10 ? '0' : '')+d.getMinutes();
var s = (d.getSeconds()<10 ? '0' : '')+d.getSeconds();

console.log(">>", frame);
console.log( ""+h+"-"+m+"-"+s+"-"+dd+"-"+MM+"-"+yyyy);
var recadd = frame.remote64; //source address
console.log(recadd);
if(recadd!=null){
recadd = frame.remote64;
var frame_obj_ack = {
type: 0x10,
id: 0x01,
destination64: recadd ,
broadcastRadius: 0x00,
options: 0x00,
data: ""+h+m+s+dd+MM+yyyy
};
serialport.write(xbeeAPI.buildFrame(frame_obj_ack));
console.log(recadd);

    }                
});

});

錯誤

events.js:160
      throw er; // Unhandled 'error' event
      ^

Error: Error Resource temporarily unavailable Cannot lock port
    at Error (native)