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串行数据通信

通信是共享信息、想法或观点的方式。它是发生在2个或更多人亦或是设备间的双向行为。它的定义是：通信是传送方和接收方利用媒介传送信息的过程，在此过程中信息被传送方和接收方同时理解。通信需要彼此之间的合作与协同。因此，若要实现一次成功的通信，通信双方必须使用同一种语言，唯有如此数据才得以交换。

4.1通信过程

4-1：通信过程

在一个数字通信系统中，数据传输有两种方式：
并行

串行

4.2.1并行通信

在并行通信中，数据通过通信连接装置同时进行传输。每个信号每个比特都是一起被传输出去的。一个并行端口通常能够通过8条缆线一次性接收8比特数据。这种数据传输方式十分迅速，但有个问题是会同时消耗大量缆线。将电脑与打印机连接实现的就是一个并行端口应用。

4.2.2串行通信

串行通信是将数据一个一个传送的过程。利用通信通道，每次只能循序传输一个信号中的一个比特。串行端口使用一条缆线一次只收发一比特数据。尽管串行通信比并行通信需要花费更多的时间，但它仅需少量缆线就能实现数据的成功传输。绝大多数网络设备都应用串行通信，例如键盘、鼠标、调制解调器、设备终端等。

Communication Serial Data
Published: 23, March 2015

Communication is the method to share information, ideas or opinions. It is a two-way action between two or more people or devices. It is defined as follows

“Communication is the process of transferring information from a sender to a receiver with the use of a medium in which the communicated information is understood by both sender and receiver”.[5]

Communication allows collaborating and cooperating with each other. So in order to perform successful communication it is necessary that both the parties understand a common language so that the data can be exchanged.

4.1Communication Process

Figure 4-1: Communication Process

4.2Communication Networks

In a digital communications system, there are two methods for data transfer:

Parallel
Serial
4.2.1Parallel Communication

In Parallel communication data is transmitted over a communication link simultaneously. All the bits of each symbol which are to be sent are transmitted together. A parallel port usually sends and receives data eight bits at a time over 8 separate wires. This method of data transfer is quick but using large number of wires simultaneously is a problem. Connecting a PC to a printer is the example where parallel port is used.

4.2.2 Serial Communication

Serial communication is the process of sending data one by one. Each bit of symbol is sent one bit at one time, sequentially, over a communication channel .A serial port sends and receives data one bit at a time over one wire. Although the time require by serial communication is much more than that in parallel communication, but only a few wires are required to send data successfully. Serial communications include most network devices, keyboards, mice, Modems, and terminals.

4.2.3 Difference between Parallel and Serial

In order to establish a communication link between two devices there may be serial or parallel communication. A parallel link transmits several streams of along communication channel whereas a serial link transmits a single stream of data.

It seems that parallel communication is much better and efficient than serial communication. But normally serial communication is more common in use as it is cheaper to implement and fewer wires are required to send data. Furthermore, serial communication allows sending data over longer distances.

4.3Description of Serial Communication

Serial communication is the process of transmitting data between a computer and a peripheral device such as a programmable instrument or even another computer.

Serial communication i