node.js<-&燃气轮机；带有串行端口的arduino。错误资源暂时不可用无法锁定端口

当号码第一次从NodeJS发送到Arduino时，我看到以下错误：

错误资源暂时不可用无法锁定端口

我使用Linux

我首先更新一些值（在web服务器中），然后串口捕获该值， 所以我可以在Arduino串行监视器中看到值

但是在我再次更新一些值之后，它会导致一个错误

这是NodeJS代码：

var serialport = require('serialport'), 

SerialPort = serialport.SerialPort, 
portName = '/dev/ttyACM0',       
portConfig = {
    baudRate: 9600,
    // call myPort.on('data') when a newline is received:
    //parser: serialport.parsers.readline('\n')
};

... (code) ... 

pool.getConnection(function(err,connection)
{
    var sql = "update value set temperature=? , humidity=? where idx=?";
    connection.query(sql,[temperature,humidity,idx],function(err,result)
    {
        console.log(result);
        if(err) console.error("update errrr : ",err);
        var myPort = new SerialPort(portName, portConfig);
        myPort.on('open', openPort);

    function openPort() {
          var temp = temperature; 
            console.log('port open');
              console.log('baud rate: ' + myPort.options.baudRate);

        function sendData() {

        //myPort.write(temp.toString());        for(var i=0; i<temp.length; i++) {
      myPort.write(new Buffer(temp[i], 'ascii'), function(err, results) {
        });

      }

        console.log('Sending ' + temp + ' out the serial port');
    }       setTimeout(sendData, 500);      myPort.close

   }
     res.redirect('/');
         connection.release();
    });

}); });

我找到了答案

function openPort() {
            var temp = temperature; 
        console.log('port open');
        console.log('baud rate: ' + myPort.options.baudRate);
        setTimeout(sendData, 1);
        function sendData() {myPort.write(new Buffer(temp, 'ascii'), function(err, results) {});
            console.log('Sending ' + temp + ' out the serial port');
    myPort.close(function () {console.log('port Closed.');});
        }
    }

我找到了答案

function openPort() {
            var temp = temperature; 
        console.log('port open');
        console.log('baud rate: ' + myPort.options.baudRate);
        setTimeout(sendData, 1);
        function sendData() {myPort.write(new Buffer(temp, 'ascii'), function(err, results) {});
            console.log('Sending ' + temp + ' out the serial port');
    myPort.close(function () {console.log('port Closed.');});
        }
    }