如何为 SerialDevice 创建一个 "DataReceived" 事件？

Question

我正在使用 SerialDevice class 将 RS-485 与我的串行端口一起使用。它目前没有接收数据的事件。我目前必须使用 DataReader 轮询 Listener，它并不总是捕获其缓冲区中的所有数据。

我正在寻找一种方法来为 SerialDevice class 创建接收器事件，这样我就不必进行轮询，并且可以在收到正确数据时立即触发。

我目前的方法：

async void Initialize()
{
        DeviceInformationCollection devices = await DeviceInformation.FindAllAsync();
        if (devices.Count > 0)
        {
            for (int i = 0; i < devices.Count; i++)
            {
                if (devices[i].Id.Contains("PNP0501#2"))
                {
                    GpioStatus = string.Format("Connecting... {0} found", devices[i].Id);
                    DeviceInformation deviceInfo = devices[i];
                    serialDevice = await SerialDevice.FromIdAsync(deviceInfo.Id);
                    serialDevice.BaudRate = 9600;
                    serialDevice.DataBits = 8;
                    serialDevice.StopBits = SerialStopBitCount.Two;
                    serialDevice.Parity = SerialParity.None;
                    serialDevice.Handshake = SerialHandshake.None;
                }
            }
        }
        Listen();
}


        Initialize();
        DataReader dataReader;
        SerialDevice serialDevice;
        CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
        const uint ReadBufferLength = 1024;

        async void Listen()
        {
            try
            {
                dataReader = new DataReader(serialDevice.InputStream);
                dataReader.InputStreamOptions = InputStreamOptions.Partial;

                while (true)
                {
                    await ReadAsync(cancellationTokenSource.Token);
                }
            }
            catch
            {
                GpioStatus = "Failed to listen";
            }
        }

        private async Task ReadAsync(CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();

            Task<UInt32> loadAsyncTask = dataReader.LoadAsync(ReadBufferLength).AsTask(cancellationToken);

            UInt32 bytesRead = await loadAsyncTask;
            GpioStatus = dataReader.ReadString(bytesRead);
        }

如有任何想法，我们将不胜感激！

Answer 1

因为它是一个串行协议，所以你需要在输入时进行解释。如果预期的第一件事是（比如说）4 字节长度，然后是数据包的其余部分，那么：

while (dataReader.UnconsumedBufferLength > 0)
{
  // Note that the call to readString requires a length of "code units" 
  // to read. This is the reason each string is preceded by its length 
  // when "on the wire".
  uint bytesToRead = dataReader.ReadUInt32();
  receivedStrings += dataReader.ReadString(bytesToRead) + "\n";
}

代码片段取自：https://docs.microsoft.com/en-us/uwp/api/windows.storage.streams.datareader

如何为 SerialDevice 创建一个 "DataReceived" 事件？

How to create a "DataReceived" Event for SerialDevice?

c#

events

serial-port