Communication protocols in the industry

Sarah Kolberg | May 29, 2024

How do communication protocols in the industry differ from office environments? What industrial communication protocols are there and what are their special features? This blog post provides more information about fieldbus protocols and Industrial Ethernet.

Why do you need industrial communication protocols?

Communication protocols define rules and procedures to ensure effective and reliable communication between individual network components. Industrial communication protocols are intended for the exchange of data and information as well as the co-operation of individual components of industrial systems. A common language and structure are defined for systems, machines, computers, etc. to ensure trouble-free operation. The further development of these protocols is important for process optimization and new value chains in industry.

Emergence of industrial communication protocols

The development of industrial communication protocols dates to the 1960s and is closely linked to the emergence of the first programmable logic controllers (PLCs), which communicated via a serial interface using a customized bus protocol, i.e. with proprietary software. These are still used today for components for which no connection or other expansion is planned.

However, if connectivity or the possibility of future expansion is required, standard protocols are needed that have been created for this purpose. These communication protocols were initially developed based on specific features or groupings of the respective devices, e.g. for controllers or sensors. These serial protocols are still used in industrial environments today and are known as fieldbus protocols. Around the 1990s, numerous initiatives were undertaken in the industrial environment - first initiated by the automotive industry - from which today's Industrial Ethernet protocols emerged.

Categorization of industrial communication protocols

Fieldbus protocols

Fieldbus protocols are serial communication protocols that enable systems in the field such as sensors, motors, or actuators to exchange information with PLCs.

 

Examples of fieldbus protocols

This list is not exhaustive and only contains a selection.

 

Modbus: used in industrial automation, communication between PLCs and field devices

Profibus: used in process control, factory automation & common standard in drive communication, supports fast data transmission

CAN-open (Controller Area Network): short system response time, high data security, multi-master capability

DeviceNet: network protocol for connecting sensors and actuators to PLCs, based on CAN

CC-Link: is primarily used in the Asian region, communication between PLC and fieldbus devices

Extension of Ethernet protocols for industry

The successors to the fieldbus protocols represent a modification of the standard Ethernet for industry. They are designed to ensure the transmission of production data for a specific operation at the exact time required to enable trouble-free operations.These are open standards and real-time protocols that often require a hardware interface.

Examples of industrial protocols (Ethernet extension):

This list is not exhaustive and contains only a selection.

Profinet: developed by Siemens, communication between control systems, I/O and industrial components in real time, used in automation, uses IP/TCP for communication

Ethernet/IP: developed by Rockwell Automation, integration of Ethernet-based devices in industrial environments, simple integration into existing networks possible, high data transfer rates

EtherCAT (Ethernet for Control Automation Technology): developed by Beckhoff Automation, fast communication between decentralized field devices and PLCs, popular due to simple handling and excellent performance

Modbus-TCP: developed by Schneider Electric, communication with Modbus devices via Transmission Control Protocol (TCP), works according to the master-slave principle, main area of application in control technology.

(Ethernet) POWERLINK: Transmission of process data in industrial automation, real-time data transmission in the microsecond range

Difference between standard Ethernet and Industrial Ethernet

Ethernet in office environments is exposed to significantly fewer interference factors than is the case with Industrial Ethernet. Here, vibration or heat can present networks with challenges. Appropriate robustness is required to survive in an industrial environment. Industrial Ethernet is designed to prevent errors in the production process or to react quickly in the event of a fault. The protocols are tailored to the requirements of industrial plants. This can also be seen, for example, in the better handling of high data transmission rates or data collisions.

Another important difference is the determinism of Industrial Ethernet, i.e. the dependence on a time component. If there are delays in data transmission, this can hinder operations. This could mean production stops, downtime or machine malfunctions and must therefore be prevented at all costs.

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