Technical Guides

Industrial Communication Networks – Overview

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1. What is the Industrial Communication Network?

-Data communication refers to the conversion of information or data, mainly in digital format, from a transmitter to a receiver via a link (be it copper wire, coaxial cable, optical cable or whatever Any other means) connect these two devices.
-Traditional communication networks are used to enable data transfer between computers, computers and its peripherals and other devices. On the other hand, industrial communication networks are a special type of network made to handle real-time control and data integrity in harsh environments on large installations.

-Examples of industrial communication networks include Ethernet, DeviceNet, Modbus, ControlNet, etc.
Three important control mechanisms are used in the field of industrial automation: Programmable Logic Controllers (PLC), Supervisory Control and Data Acquisition (SCADA) and Distributed Control System (DCS). All of these components communicate with field meters, smart field devices, monitoring control computers, distributed I / O controllers and HMI interfaces.
-The means of transmission for data transmission and control signals may be wired or wireless. In the case of wired transmission, the cable used may be a twisted pair, coaxial cable or fiber optic. Each network cable has its own electrical characteristics that may be less or more suitable for a particular type of network or environment. In the case of wireless transmission, communication is done via radio waves.

2. Decentralized in industrial communication network

In the manufacturing industry or processes, information or data flows from the school level to the management-operation level (bottom to top) and vice versa. Different levels have to handle different requirements of a specific level. Therefore, it is clear that no unique communication network address requirements are required for each level. Therefore different levels may use different networks based on requirements such as data volume, data transfer, data security, etc. Based on function, industrial communication network is classified into three main levels:

Device Level:

+ This lowest level includes field devices such as sensors and actuators of processes and machines. The task of this level is to transfer information between these devices and technical process components such as PLC. The transfer of information can be digital, analogue or hybrid. The measured values may last for a long time or over a short period of time.

+ To provide decentralized field communication, 4-20 mA current, point-to-point communication protocols are widely used. These networks include parallel, multi-wire cables as a means of transmission. Common serial communication protocol standards used at this level include RS232, RS422 and RS485. There are many other school-level communication networks available that describe various factors such as response time, message size, etc.

+ Today, fieldbus technology is the most sophisticated communication network used at the field level because it facilitates distributed control between various smart field controllers and controllers. This is a two-way communication system in which many variables are taken care of by single transmission. Different fieldbus types include HART, ControlNet, DeviceNet, CAN Bus, Profibus and Foundation Fieldbus.

Control Level:

-This level includes industrial controllers such as PLC, distributed control units, and computer systems. The tasks of this level include configuring automation devices, downloading program data and processing data variables, adjusting variables, monitoring control, displaying variable data on the HMI, calendar storage history, etc. Therefore, the control level requires characteristics such as short response time, high speed transmission, short data length, machine synchronization, continuous use of important data, etc.
-Local area networks (LAN) are widely used as communication networks at this level to achieve the desired properties. Ethernet with TCP/IP protocol is mainly used as control level network to connect control units with computers. In addition, this network acts as a control bus to coordinate and synchronize between different controllers. Some fieldbuses are also used at this level as control buses such as Profibus and ControlNet.

Information Level:

This is the highest level of the industrial automation system that gathers information from lower levels, such as the control level. It handles large volumes of data that are not used continuously or limit time. Large-scale networks exist at this level. Therefore, Ethernet WANs are often used as information level networks for factory planning and management information exchange. Sometimes these networks can connect to other industrial networks through gateways.

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