Communication System

In order for a computer or controller to be helpful in automating a manufacturing system, it should be able to communicate along with external devices. These external devices might be actuators for controlling a process, sensors for monitoring a process, or the external device might be another computer. Information exchanges among devices need the standardization of the language of communication. The American Standard Code for Information Exchange (ASCII) is a language and it is utilized by most computer manufacturers. The ASCII code described the relationship among alphabetic, numeric, and punctuation characters and their equivalent binary string. ASCII provides binary symbols as well for control actions, such like carriage returns (CR) & the line feed (LF).

There are fundamentally two primary techniques of data transfer utilized in computer interfacing:

• Programmed data transfer &
• Direct memory access (DMA).

Each technique used a different set of software and hardware protocols. There are two primary methods of transferring binary data -serial or parallel data transmission. Parallel data communications permits several bits to be transferred simultaneously across the interface between communication devices, whereas serial data communication, as the name implies, transmits data one bit at a time. A communication system consists of many LANs for networking, certain specified protocols, database management system etc.