This documentation is archived and is not being maintained.

SerialPort.Write Method (Char[], Int32, Int32)

Writes a specified number of characters to the serial port using data from a buffer.

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

public void Write(
	char[] buffer,
	int offset,
	int count


Type: System.Char[]
The character array that contains the data to write to the port.
Type: System.Int32
The zero-based byte offset in the buffer parameter at which to begin copying bytes to the port.
Type: System.Int32
The number of characters to write.


The buffer passed is null.


The specified port is not open.


The offset or count parameters are outside a valid region of the buffer being passed. Either offset or count is less than zero.


offset plus count is greater than the length of the buffer.


The operation did not complete before the time-out period ended.

Use this method when you want to write to a character buffer to create output to a serial port.

If there are too many bytes in the output buffer and Handshake is set to XOnXOff then the SerialPort object may raise a TimeoutException while it waits for the device to be ready to accept more data.

By default, SerialPort uses ASCIIEncoding to encode the characters. ASCIIEncoding encodes all characters greater than 127 as (char)63 or '?'. To support additional characters in that range, set Encoding to UTF8Encoding, UTF32Encoding, or UnicodeEncoding.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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