C＃Visual Studio每毫秒通过串行端口读取一个数据包

Question

I have a window form application that needs to read in a byte array once every ms. The byte array varies in size, but will never be longer than 36 bytes. The code I currently have seems to omit some of the data packages. One of the bytes in the package is a count, so I can tell some of the packages are being missed. After serialPort1.Read(data, 0, bytesToRead) the rest of the code is just to process the byte array into an int array and add it to a list. That code all works like I expect it to.

private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
{

       int bytesToRead = serialPort1.BytesToRead; 
       byte[] data = new byte[bytesToRead];
       serialPort1.Read(data, 0, bytesToRead); 

       data = replaceBytes(data);
       long[] dataIntigerValuesPlusCountValue = convertDataToInt(data);
       List<long> dataIntigerValuePlusCountValueList = dataIntigerValuePlusCountValue.OfType<long>().ToList();
       dataList.Add(dataIntigerValuePlusCountValueList);

}

Answer 1

I have a window form application that needs to read in a byte array once every ms.

First off, you shouldn't have to read 'every ms', you'll lock up the UI if you're in the UI thread (which you are since you're not using threading).

The byte array varies in size, but will never be longer than 36 bytes.

Instead of trying to read a single packet every MS, you should buffer data, 36 bytes at a time, and then process it. Eg Ready 36 bytes, find the byte which tells you how long the packet should be, then process that many bytes. On your next serial port read, concatenate the array of any unused bytes with the next 36 bytes you read (your buffer array size should be at least 72 bytes, and on each loop, you should check if the current size is greater than 36, and if it is, loop an additional time so that at a given time, you have at most 1 full packet in the byte array buffer).

Also, instead of blocking the UI thread, and instead of utilizing threads, you should use async/await continuously read read data and then process your data that way. How to continually read data asynchronously .

That way you would get the packet size, then wait for the buffer to be the appropriate size, then you process the data.

The way you're currently doing it will drop the extra data buffered and desync your connection. That said, you should also try and use a flag byte (or a newline character) to signify the start or end of packet. Obviously if it's not your hardware you can't control that, but if you can, that would guarantee the stream never desyncs.

TL:DR: Timing is unreliable, just process the packets as they are received.