.NET CORE Serial Class 在使用 tty 端口发布到 Linux 机器时未读取 BaseStream 或 ReadBuffer 中超过 4KBytes 的数据

Question

我构建了一个串行端口文件传输 .NET CORE 3.0 应用程序，它在 windows 上运行良好，但在 linux 上只能读取少量数据。基本上我从一台机器传输数据，接收机器读取数据是这样的：

        _serialPort.ReadBufferSize = 7000000;
...more setup code 

        Console.WriteLine("Serial receiver started at " + DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ss.fff", CultureInfo.InvariantCulture) + " Collecting and decoding file data for 4 minute intervals. Please wait...");
        Console.WriteLine("Header search pattern: " + BitConverter.ToString(BitConverter.GetBytes(header)));
        int sleepTimeMiliseconds = (240000 - (int)stopwatch.Elapsed.TotalMilliseconds < 1) ? 0 : 240000 - (int)stopwatch.Elapsed.TotalMilliseconds;
        Thread.Sleep(sleepTimeMiliseconds); // wait for about 4 minutes for the data to come in.
        byte[] dataBuffer = new byte[_serialPort.ReadBufferSize];

        //read data then discard buffer to get new data from the transmitting machine
        if (!_serialPort.IsOpen) // serial port could close when operating system sleeps
            _serialPort.Open();
        _serialPort.Read(dataBuffer, 0, dataBuffer.Length);
        //HundredKBBuffer = Convert.FromBase64String(_serialPort.ReadExisting());
        _serialPort.DiscardInBuffer();
        stopwatch.Restart();
        Console.WriteLine("Data buffer size in bytes: " + dataBuffer.Length);
        DecodeFileData(dataBuffer, header, trailer);

我也尝试过使用 _serialPort.BaseStream.Read(dataBuffer, 0, dataBuffer.Length); 而不是 _serialPort.Read(dataBuffer, 0, dataBuffer.Length);，但同样的问题发生了。我从未在缓冲区中看到任何超过 4096 的字节，所以我不确定如何在 linux 环境中实现这一点。缓冲区大小是否更小且不可更改？我已经使用了 _serialPort.ReadBufferSize = 7000000; 但它似乎并没有帮助解决这个问题。 linux 机器是 CentOS 或 Redhat

Answer 1

4KBytes 是 tty 缓冲区的限制。内核有一个 4096 字节的内部缓冲区。如果此缓冲区已满并且新字节到达串行端口，则缓冲区中最旧的字节将被覆盖并因此丢失。

我解决了 .NET CORE 3.0 不允许我设置 _serialPort.ReadBufferSize 的问题，方法是基本上使用 "stream byte reader" 方法并沿我的自定义字节 [] 缓冲区递增我的当前索引在我之前的读取操作中读取了很多字节（轮询以填充我的自定义缓冲区）。

                    byte[] dataBuffer = new byte[3000000]; // big enough buffer
                    bool singleReadIterationFinished = false;
                    while (!singleReadIterationFinished)
                    {
                        Task<int> bytesReadFromPort = _serialPort.BaseStream.ReadAsync(dataBuffer, bufferOffset, dataBuffer.Length - bufferOffset); // read as many bytes as available at a time

                        //other code can go here since the thread isn't blocked 

                        bufferOffset += bytesReadFromPort.Result; // From docs.Microsoft: Calling the result properties get accessor will block the calling thread until the asyncrhonous operation is complete; this is equivalent to calling 'Wait' method.
                        if (bufferOffset > 2000000) // wait for 2megabytes of data. change this to megabytes. 
                        {
                            Console.WriteLine("Read a total of : " + bufferOffset + " Bytes");
                            byte[] copyBuffer = new byte[dataBuffer.Length];
                            Array.Copy(dataBuffer, 0, copyBuffer, 0, dataBuffer.Length);
                            DecodeFileData(copyBuffer, header, trailer); // need to call this asyncronously
                            singleReadIterationFinished = true;
                        }
                    }

.NET CORE Serial Class 在使用 tty 端口发布到 Linux 机器时未读取 BaseStream 或 ReadBuffer 中超过 4KBytes 的数据

.NET CORE Serial Class not reading data past 4KBytes in BaseStream or ReadBuffer when published to Linux machine using tty ports

c#

linux

embedded

serial-port

.net-core