SerialPort.Write Method (Byte, Int32, Int32)
Writes a specified number of bytes to the serial port using data from a buffer.
Assembly: System (in System.dll)
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 byte buffer to create output to a serial port.
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.