Asynchronous data transmission (also known as start-stop data transmission) is a communication method where each end of the transmission begins data flow only when the other has finished. Unlike synchronous data transmission, which requires that both ends of the communication be active and synchronized at the same time, asynchronous data transmission allows one end of the communication to remain either idle or inactive while the other end is active.
Asynchronous data transmission typically uses a start signal (or “start bit”) from the sending side of the transmission to initiate data flow, followed by the actual data bits before signaling the other end with the stop signal (or “stop bit”). Synchronization between sender and receiver is maintained through required pause between each section of data (a part of the transmission known as the “inter-character gap”). This makes sure that when the data is received by the other end, it is received in the same order it was sent.
Obviously, the opposite of asynchronous data transfer is synchronous data transmission. In this form of data transfer, both ends of the communication need to remain synchronized and active in order to maintain communication. Asynchronous data transmission, on the other hand, can be used to maintain communication with devices that can’t guarantee a consistent and continuous signal, such as serial ports.
Because one end can remain idle while the other is active, asynchronous data transmission is especially suitable for applications that are required to send or receive large amounts of data. For example, many home networking technologies such as Ethernet and Wi-Fi use asynchronous data transmission as their core data-transfer mechanism as a means of meeting large-scale communication demands. Application and services such as file downloads and video streaming also make use of asynchronous data transmission in order to accurately receive the large chunks of data associated with their specific tasks.
In short, asynchronous data transmission is a form of communication that is used when devices are required to send and receive large amounts of quickly transfered data. This data is broken into smaller sections and sent one after another with a time delay between each package. Asynchronous data transmission method is often used in many home networking technologies, file downloads, and video streaming applications.