Share via

SerialPort.ReadByte Method


Synchronously reads one byte from the SerialPort input buffer.

 int ReadByte();
public int ReadByte ();
member this.ReadByte : unit -> int
Public Function ReadByte () As Integer


The byte, cast to an Int32, or -1 if the end of the stream has been read.


The specified port is not open.

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


No byte was read.


This method reads one byte.

Use caution when using ReadByte and ReadChar together. Switching between reading bytes and reading characters can cause extra data to be read and/or other unintended behavior. If it is necessary to switch between reading text and reading binary data from the stream, select a protocol that carefully defines the boundary between text and binary data, such as manually reading bytes and decoding the data.


Because the SerialPort class buffers data, and the stream contained in the BaseStream property does not, the two might conflict about how many bytes are available to read. The BytesToRead property can indicate that there are bytes to read, but these bytes might not be accessible to the stream contained in the BaseStream property because they have been buffered to the SerialPort class.

Applies to