SerialPort.ReadTimeout Property

 

Gets or sets the number of milliseconds before a time-out occurs when a read operation does not finish.

Namespace:   System.IO.Ports
Assembly:  System (in System.dll)

<BrowsableAttribute(True)>
Public Property ReadTimeout As Integer

Property Value

Type: System.Int32

The number of milliseconds before a time-out occurs when a read operation does not finish.

Exception Condition
IOException

The port is in an invalid state.

- or -

An attempt to set the state of the underlying port failed. For example, the parameters passed from this SerialPort object were invalid.

ArgumentOutOfRangeException

The read time-out value is less than zero and not equal to InfiniteTimeout.

The read time-out value was originally set at 500 milliseconds in the Win32 Communications API. This property allows you to set this value. The time-out can be set to any value greater than zero, or set to InfiniteTimeout, in which case no time-out occurs. InfiniteTimeout is the default.

System_CAPS_noteNote

Users of the unmanaged COMMTIMEOUTS structure might expect to set the time-out value to zero to suppress time-outs. To suppress time-outs with the ReadTimeout property, however, you must specify InfiniteTimeout.

This property does not affect the BeginRead method of the stream returned by the BaseStream property.

The following code example demonstrates the use of the SerialPort class to allow two users to chat from two separate computers connected by a null modem cable. In this example, the users are prompted for the port settings and a username before chatting. This code example is part of a larger code example provided for the SerialPort class.

Public Shared Sub Main()
    Dim name As String
    Dim message As String
    Dim stringComparer__1 As StringComparer = StringComparer.OrdinalIgnoreCase
    Dim readThread As New Thread(AddressOf Read)

    ' Create a new SerialPort object with default settings.
    _serialPort = New SerialPort()

    ' Allow the user to set the appropriate properties.
    _serialPort.PortName = SetPortName(_serialPort.PortName)
    _serialPort.BaudRate = SetPortBaudRate(_serialPort.BaudRate)
    _serialPort.Parity = SetPortParity(_serialPort.Parity)
    _serialPort.DataBits = SetPortDataBits(_serialPort.DataBits)
    _serialPort.StopBits = SetPortStopBits(_serialPort.StopBits)
    _serialPort.Handshake = SetPortHandshake(_serialPort.Handshake)

    ' Set the read/write timeouts
    _serialPort.ReadTimeout = 500
    _serialPort.WriteTimeout = 500

    _serialPort.Open()
    _continue = True
    readThread.Start()

    Console.Write("Name: ")
    name = Console.ReadLine()

    Console.WriteLine("Type QUIT to exit")

    While _continue
        message = Console.ReadLine()

        If stringComparer__1.Equals("quit", message) Then
            _continue = False
        Else
            _serialPort.WriteLine([String].Format("<{0}>: {1}", name, message))
        End If
    End While

    readThread.Join()
    _serialPort.Close()
End Sub

Public Shared Sub Read()
    While _continue
        Try
            Dim message As String = _serialPort.ReadLine()
            Console.WriteLine(message)
        Catch generatedExceptionName As TimeoutException
        End Try
    End While
End Sub

.NET Framework
Available since 2.0
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