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SerialPort.Open Method

Note: This method is new in the .NET Framework version 2.0.

Opens a new serial port connection.

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

public void Open ()
public void Open ()
public function Open ()

Exception typeCondition

InvalidOperationException

The specified port is open.

ArgumentOutOfRangeException

One or more of the properties for this instance are invalid. For example, the Parity, DataBits, or Handshake properties are not valid values; the BaudRate is less than or equal to zero; the ReadTimeout or WriteTimeout property is less than zero and is not InfiniteTimeout.

ArgumentException

The port name does not begin with "COM".

- or -

The file type of the port is not supported.

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.

UnauthorizedAccessException

Access is denied to the port.

Only one open connection can exist per SerialPort object.

The best practice for any application is to wait for some amount of time after calling the Close method before attempting to call the Open method, as the port may not be closed instantly.

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.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

.NET Compact Framework

Supported in: 2.0

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