正在为注册事件处理程序System.IO.端口.SerialPort SerialDataReceivedEventHandler

我有个奇怪的问题。我正在尝试编写从.Net核心控制台应用程序的串行端口读取的代码。我正在使用Microsoft的System.IO.端口来自NuGet的v4.7.0库。我从这里复制了代码:

https://docs.microsoft.com/en-us/dotnet/api/system.io.ports.serialport.datareceived?view=dotnet-plat-ext-3.1

但是,当我将代码粘贴到Visual Studio中时,我立即收到以下错误:

我的代码非常简单:

using System;
using System.IO.Ports;

public class SerialComms
{
    SerialPort _serialPort;

    private void SetupSerialPort()
    {
        _serialPort.PortName = "/dev/ttyS0";
        _serialPort.BaudRate = 115200;
        _serialPort.Parity = Parity.None;
        _serialPort.DataBits = 8;
        _serialPort.StopBits = StopBits.One;
        _serialPort.Handshake = Handshake.None;
        _serialPort.WriteTimeout = 500;
        _serialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler);
        _serialPort.Open();
    }

    private void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
    {
        SerialPort sp = (SerialPort)sender;
        string indata = sp.ReadExisting();
        Console.WriteLine("Data Received:");
        Console.Write(indata);
    }
}

我花了好几个小时在这上面,一辈子都搞不清我到底错在哪里。据我所知,事件处理程序的签名是正确的。有什么想法吗?