The industry has been developing with significant momentum in recent years. Therefore, in automation technologies, sensors, actuators, valves, relays, etc. While the devices communicate with each other, PLC and computers, the communication between them becomes problematic. Many Industrial Communication standards have emerged to solve this problem.
Industrial communications aim to transmit data from the field to the control level. Industrial Communications, state–of–the–art wireless technologies, and compatible solutions with cybersecurity increase the availability and security of systems integrated here into the network. Network protocols and Fieldbus systems such as PROFINET, OPC UA, PROFIBUS, and INTERBUS provide efficient communication.
Today, the basic principle that many people and organizations work on is communication or open to everyone and free helpful, rather than interconnecting machines to create protocols.
The protocols used in Electronic Communication are so numerous that when there is an obligation to communicate between two systems that carry a different language, the existing ones. Difficulties manifest themselves immediately. Especially in the exchange of technical information, this becomes even more dangerous.
There is no natural nen to create a more comprehensive system by combining various techniques that make up the focal point of communication. Instead, this communication provides the necessary data to be studied required for compilation and use.
Industrial Communication Protocols
The industry is developing and growing day by day. Therefore, communication between devices and machines is getting more and more difficult. As a solution to this problem, specific standards have been introduced in the industry regarding transmission. These standards are also protocols.
Data collection, processing, and analysis processes between systems are carried out due to the communication of automation systems with PLC and computer systems. For the communication between the transmitter and the receiver to be fast and reliable, some rules must be determined according to the devices used. With the determination of these rules, communication protocols are determined. The specific features of all protocols have been selected and fixed. These protocols must also produce devices.
Communication protocols are divided into Open Systems and Closed System communication protocols.
Closed System Communication Protocols
These are the company’s communication protocols to provide communication only between their products.
Open System Communication Protocols
It is a communication protocol developed to communicate products that exhibit the same functions, independent of the brand. In this protocol, products between different companies can connect.
Open system communication protocols are divided into 8;
Fieldbus is a field network consisting of automation products and computers. Fieldbus, which provides high–resolution measurement and high reliability, also has the feature of self–testing, and there is no rounding loss in this protocol. It is a protocol with a severe market share due to the multifunctional field units. It can communicate PLC systems among themselves with the loops it establishes. At the same time, thanks to these loops, in case of any malfunction between significant–scale electronic elements in the facilities, it can detect the location of the malfunction in advance and show it to the user.
Profibus, which enables the communication between devices from different manufacturers without a particular interface, is a manufacturer–independent open field protocol. It provides fast data exchange. Thus, they are widely preferred in critical applications requiring high speed and complex communication works. It is designed for large–scale production and process automation. It is possible to change devices in this protocol.
According to usage area and type, Profibus offers three different communication protocols (DP – PA – FMS).
- Profibus DP (DP–Decentralized Periphery/Distributed Environment):
Profibus DP, which uses RS485 or fiber optic infrastructure as its physical structure, is the most widely used communication type.
It is preferred because of its speed, efficiency, and low connection cost features. In addition, communication with centrally distributed devices and intelligent field devices can be achieved.
- Profibus FMS (FMS–Fieldbus MessageSpecification/Field Bus Message Definition):
Profibus FMS, a general communication type, uses RS485 and fiber optic infrastructure as physical communication structures. It offers advanced application functions for communication between intelligent control devices. The rapid increase in the development and use of TCP/IP affects FMS negatively.
- Profibus PA (PA–Process Automation):
Profibus PA is working on the same master as DP is generally used in process automation.
Modbus, which MODICON created as a serial communication protocol between PLCs, is the most used protocol in the industry, thanks to its simple and robust structure. It is a server–client–based protocol that can communicate between different devices. Therefore, it is a network system where data can be received from a device and collected in a data center. Furthermore, it is an open protocol. Therefore, manufacturers can use it without any charge.
CANBus (Controller Area Network Bus / Control Area Network Bus) protocol, developed by Robert Bosch, is intended to transfer data with a single cable instead of multiple cables. It is widely used in the automotive industry. Statistically, it has been determined that one message error can be made in 100 years. Thanks to this high reliability, it is also used in industrial control applications. It has a communication speed of up to 1Mbit/s in application areas such as intelligent buildings and laboratory environments, intelligent sensors, engine control, automobile electronics, machine control units. At the same time, in this protocol, all units have equal priority in sending data to the line.
With DeviceNet, an industrial communication protocol developed by Allen–Bradley for intelligent sensors and actuators, low–level devices can be connected and communicated with higher–level devices such as PC or PLC. Built on the CAN architecture, DeviceNet is open and cost–effective. In addition, DeviceNet, which has a stable structure designed to meet the needs of reliability and performance, is a proven protocol with its sound system.
AS–I (Actuator Sensor–Interface) is an industrial communication protocol used in PLC, DCS, and PC–based automation systems. It is the most straightforward alternative to parallel wiring. It has not yet been fully standardized. However, it is a very reliable system, as well as being extremely simple and inexpensive. AS–I can also exist as a logical component group of another subsystem in the automation system to which it can be directly connected.
It is a serial bus system that transfers data between control systems (PC, PLC, automation controllers, etc.)—developed by Phoenix Contact company. The system, which performs bidirectional data communication, provides communication with closed area topology.
HART (Highway Addressable Remote Transducer) is the protocol that allows us to send and receive digital information using analog cables between intelligent systems and the monitoring system. It provides bidirectional data communication between central systems and smart devices. The maximum transmission rate depends on the physical layer used.