TimeoutException in serial port

Question

 

I am using in "SerialPort_DataReceived" event to received data from serial port.

I would like to use "TimeoutException" for "ReadTimeout" and set it to 1 sec.

How can I integrate "TimeoutException" with "SerialPort_DataReceived"?

 

 

See sample relevant code:

 

 

'Form

Public Class Serial_Port_Form

 

Private Sub SendButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SendButton.Click

        Dim XmtBuffre(5) As Byte

       

        XmtBuffre(0) = ENUM_OPCODE_TYPE.EN_WRITE_FLASH_CMD_LSB

        XmtBuffre(1) = ENUM_OPCODE_TYPE.EN_WRITE_FLASH_CMD_MSB

 

        XmtBuffre(2) = BytesNumberLSB

        XmtBuffre(3) = BytesNumberMSB

 

 

  ChecksumLSM = ENUM_OPCODE_TYPE.EN_WRITE_FLASH_CMD_MSB Xor _

                ENUM_OPCODE_TYPE.EN_WRITE_FLASH_CMD_LSB Xor _

                      BytesNumberLSB Xor BytesNumberMSB

 

 

        For i = 0 To (XmtBuffre.Length - 3)

            ChecksumLSM = ChecksumLSM Xor XmtBuffre(i)

        Next

 

        XmtBuffre(4) = ChecksumLSM

        XmtBuffre(5) = ChecksumMSM

 

        SerialPort.Write(XmtBuffre, 0, XmtBuffre.Length)

    End Sub

 

End Class

 

 

 

'Module

Module Serial_Port_Module

 

Public Err As New IO.Ports.SerialError

Public WithEvents SerialPort As New IO.Ports.SerialPort

 

Public RxWholeBuffer As New ArrayList

 

 

Private Sub SerialPort_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort.DataReceived

       

  Count = SerialPort.BytesToRead

        Dim RxSubBuffer(0 To Count - 1) As Byte

        SerialPort.Read(RxSubBuffer, 0, Count)

 

        RxWholeBuffer.AddRange(RxSubBuffer)

End Sub

 

  End Module

 

Answer 1

 

Hopefully I have understood what you are seeking; if not, please accept my apologies.

 

The call to the Write method is blocking therefore the timeout exception can be raised by it ....

 

serialPort.WriteTimeout = 1000

Try : serialPort.Write(msg, 0, msg.Length)

Catch ex As TimeoutException ...........

End Try

 

Is that what you were seeking?

 

Richard

Answer 2

Thanks Ricdard, sorry it is not what I am looking for.

Somebody, any ideas…

Answer 3

Can you explain a little more with regards to the problem you are facing / the needs of your application?

Answer 4

My application communicates with external device under RS232 or RS485.

I need to implement the following requirements:

  

Retransmission is required when one of the following scenarios occurs:

§         Only part of the message received (not all N bytes arrived).

§         Checksum error.

§         Error occurred on communication port.

 

 Retransmission flow:

1)            Retransmission every 1 second (Timeout).

2)            Maximum 3 retransmissions – when 3 failed send Error NACK message.