Serial port ReadByte() time out exception

Question

I am working on a C# application. My application has to do serial communication with a hardware device. The device is connected with my system on "COM4" com port. Code:

serialPort = new SerialPort("COM4", 2400, Parity.Odd, 8, StopBits.One);
serialPort.WriteTimeout = 5000;
serialPort.ReadTimeout = 5000;
serialPort.Open();
serialPort.Handshake = Handshake.None;
serialPort.DtrEnable = true;
serialPort.RtsEnable = true;

After that i do a write operation, this works fine. Code:

private void WriteMessage(byte[] busMsg)
{
    BinaryWriter writer = new BinaryWriter(serialPort.BaseStream);
    writer.Write(busMsg);
    writer.Flush();
}

After write, when i do ReadByte operation, i get the timeout exception. Code:

private byte ReadAEBusMessageResponse()
{
    BinaryReader reader = new BinaryReader(serialPort.BaseStream);
    return reader.ReadByte();
}

I read somewhere on google that BaseStream might cause issue, so i tried the below code for reading but, still no luck and i am still getting the timeout exception.

private byte ReadAEBusMessageResponse()
{
    SerialPort currentPort = serialPort;
    return Convert.ToByte(currentPort.ReadByte());
}

I do get the response when i try communication with Hercules, so i assume there is no issue with response from device. What am i doing wrong with serial communication ? any help would be much appreciated.

"After write, when i do ReadByte operation" What if not to write and just read, would result be different? — Louis Go
– Louis Go, Commented Apr 8, 2020 at 8:07
let me check, but i have to do write, as it is a command which i send to the device and device respond according to that command — Waleed Naveed
– Waleed Naveed, Commented Apr 8, 2020 at 8:09
@LouisGo still getting timeout exception which is pretty obvious — Waleed Naveed
– Waleed Naveed, Commented Apr 8, 2020 at 8:15
It's possible that the device did not really get the message from system, thus there is no reply ( byte ) to read. Check SerialPort.BytesToRead after your write might help. It would help a lot if your device has ability to show received message. — Louis Go
– Louis Go, Commented Apr 8, 2020 at 8:23
getting 0 in "SerialPort.BytesToRead". The device is a real hardware device, so can not show its received message. @LouisGo — Waleed Naveed
– Waleed Naveed, Commented Apr 8, 2020 at 8:43

Mark Wille · Accepted Answer · 2021-09-13 15:57:16Z

I have only found the async event to work. I have created my own byte receive buffer and then I handle the event:

static byte[] RXbuffer = new byte[512]; //"static" so it can be used all over

public void SerialPort_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            Byte_Size = SerialPort.BytesToRead;

            SerialPort.Read(RXbuffer, 0, Byte_Size);

            /* Return to UI thread */
            this.Invoke(new EventHandler(DisplayText));                       
        }

the DisplayText is a method to print the buffer in a textbox.

private void DisplayText(object sender, EventArgs e)
        {
            int i = 0;
            byte[] Received_Bytes = new byte[Byte_Size];

            while (i < Byte_Size)
            {             
                Received_Bytes[i] = RXbuffer[i];
                i++;
            }
                

            TB_Info.AppendText("\r\nBytes Received: ");
            TB_Info.AppendText(Byte_Size.ToString());

            TB_Info.AppendText("\r\n--> ");
            TB_Info.AppendText(BitConverter.ToString(Received_Bytes));
            TB_Info.AppendText("\r\n");

           //Array.Copy(RXbuffer,Full_RX_Buff,)
        }

You can then read/manipulate the values later.

***Don't forget that in the SerialPort object that put on your form, you have to go into the properties/events dialog and assign the function that handles the receivedata event!

Collectives™ on Stack Overflow

Serial port ReadByte() time out exception

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related