What is asynchronous transfer?
Asynchronous transmission is the transmission of data in which each character is a self-contained entity with its own start and stop bits and an uneven interval between them. Asynchronous transmission is also known as start / stop transmission.
Asynchronous transmission uses start and stop bits to denote the start and end bits. The additional at the beginning and end of a transmission warns the recipient of the appearance of the first character and the last character. The asynchronous transmission method is used when data is sent as packets as opposed to a fixed data stream. The start and stop bits have opposite polarity so that the receiver can recognize when the second information packet was sent.
The two main characteristics of asynchronous communication are:
Each character is preceded by a start bit, followed by one or more stop bits
Spaces between characters are common