Question

I’m trying to handle my incoming buffer and ensure that I got all the 125 bytes of the data at each transmission. I’ve created a byte array. How can I know 125 bytes of data is being received. I tried displaying the number of bytes but it displayed different number and I’m unsure if it’s the right coding to get the number of bytes received.

Here’s my code:

void datareceived(object sender, SerialDataReceivedEventArgs e)
{
    myDelegate d = new myDelegate(update);
    listBox1.Invoke(d, new object[] { });
}


public void update()
{
    Console.WriteLine("Number of bytes:" + serialPort.BytesToRead); // it shows 155

    while (serialPort.BytesToRead > 0)
        bBuffer.Add((byte)serialPort.ReadByte());         
    ProcessBuffer(bBuffer);
}

private void ProcessBuffer(List<byte> bBuffer)
{
    // Create a byte array buffer to hold the incoming data
    byte[] buffer = bBuffer.ToArray();

    // Show the user the incoming data // Display mode
    for (int i = 0; i < buffer.Length; i++)
    {
        listBox1.Items.Add("SP: " + (bBuffer[43].ToString()) + "  " + " HR: " + (bBuffer[103].ToString()) + " Time: ");              
    }
}

Answer 1

At the moment you are reading until the local receive buffer (BytesToRead) is empty, however, a better approach is to keep a buffer and offset, and loop until you have what you need, even if that means waiting – i.e.

byte[] buffer = new byte[125]
int offset = 0, toRead = 125;

...

int read;
while(toRead > 0 && (read = serialPort.Read(buffer, offset, toRead)) > 0) {
    offset += read;
    toRead -= read;
}
if(toRead > 0) throw new EndOfStreamException();
// you now have all the data you requested