What is an asynchronous transmission?
When data is to be sent from one computer to another, it is divided into individual characters and sent the order. Such transmission is called synchronous transmission when the receiving computer uses hours that are synchronized with the clock of the sending computer. The clock creates a rhythm. If the clock is not synchronized and sending computers, the transmission form is referred to as an asynchronous transmission.
The message to be transmitted from one computer to another consists of text and non -textual characters. The characters are composed of bits. These bits are sent via electrical wires and are marked with signal levels. For the sender and the receiver that will successfully transmit bits, the rhythm must be agreed to determine the receiver the correct end of one bits and the beginning of another bits.
In asynchronous transmission, a rhythm or speed of hours is determined before the start of any communications unification. Therefore, one computer or computer device can declare that it will work at 9600 BItors per second. Other devices can only communicate with this device only if this speed is compared.
When one character must be transmitted from the sender to the receiver, the receiver must be notified to receive the character. This is done by means of a "awakening" signal at the beginning of the character. This signal is called a starting bit. To ensure that one character does not confuse with another character, bits of stops to indicate the end of each character are used. In addition to ensuring that signals do not get rid of the vicious electric noise, there is a provision for checking errors via parity bits.
The character is often composed of seven or eight bits. When transmitting one character, the initial bit was sent and then the bits of the character are sent one after another. Then a parity bit is sent and finally a bit is sent. Seven or eight -bit character requires three bits because the direction to be properly sentfrom the sending device to the reception device. This direction in asynchronous transmission can limit the amount of useful information that could be sent.
There may be changes in speed, parity methods, number of useful bits and number of bits of stops. After accepting one character, another character may come after any time. For example, the characters written on the keyboard are generated and sent over relatively long time intervals compared to the speed of the computer. The website that is sent to display could have many characters in order quickly.
Asynchronous transmission is usually preferred when data is sent less frequently. It can be used to communicate via telephone fixed lines and for simple printers. Asynchronous transmission is considered to be simpler and cheaper compared to synchronous transmission, but the latter can provide a much faster data speed.