Node.js串行端口访问被拒绝

我正在尝试通过node.js中的serialport发送字符串，代码如下：

function createSerialPort() {
  myPort = new SerialPort('COM3', {
    baudRate: 115200, dataBits: 8, parity: 'none', stopBits: 1, flowControl: 0
  })
  myPort.write("135");
}

每次我运行它时都会出现以下错误：

(node:8468) UnhandledPromiseRejectionWarning: Error: Opening COM3: Access denied
(node:8468) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:8468) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code

我到处寻找解决方法（我不熟悉使用serialport），我找到的唯一解决方案是：

function createSerialPort() {
  myPort = new SerialPort('COM3', {
    baudRate: 115200, dataBits: 8, parity: 'none', stopBits: 1, flowControl: 0
  }, true)
  myPort.write("135");
}

然后，该解决方案给了我以下信息：

(node:18192) UnhandledPromiseRejectionWarning: TypeError: callback.call is not a function
    at SerialPort._error (C:\examplepath\node_modules\@serialport\stream\lib\index.js:198:14)
    at C:\examplepath\node_modules\@serialport\stream\lib\index.js:242:12
(node:18192) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:18192) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

---

添加错误处理程序

myPort.on（'error'，function（err）{console.log（'error:'，err.message）；}）

应该修复它，因此SerialPort的第三个参数应该是函数而不是布尔值。所以这

myPort=newserialport（'COM3'，…，function（）{…}）也可以解决此问题。