Fieldbus Protocol: Revolutionizing Industrial Communication

In the realm of industrial automation, efficient and reliable communication is crucial for seamless operation. Fieldbus protocols have emerged as a game-changer, enabling enhanced connectivity and control in industrial systems. This article explores the fundamentals of fieldbus protocols, their types, working principles, advantages, and applications.

What is the Fieldbus Protocol?

Fieldbus protocol refers to a digital communication standard used in industrial automation to connect and control devices within a field network. It allows for the exchange of data between various field devices, such as sensors, actuators, IoT gateways, controllers, and other automation components. Fieldbus protocols provide a standardized framework for communication, ensuring interoperability and compatibility across different devices and manufacturers.

Industrial controller systems were previously connected using RS232 serial communications, which could only support two devices, before Fieldbus protocols. In contrast, today’s Fieldbus connections are more closely comparable to standard Ethernet connections, which allow you to connect a number of field devices to a single connection point, which would then connect to the controller.

Types of Fieldbus Protocol

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There are so many Fieldbus variant solutions available because the manufacturers of automation equipment developed proprietary Fieldbuses that compete with one another on a technical level and have varying features and functions to best address their market niche.

Due to market pressure, the majority of Fieldbuses now make the claim that they are “open”—some more so than others. The reason for this is that major end-user companies required connectivity and use of the installed control platform (e.g. PLC) to, essentially, “talk” to the control platform via the Fieldbus to specialized devices from a variety of different manufacturers.

  • AS-I Interface
  • Ethercat
  • Profinet
  • Canopen
  • Ethernet/IP
  • Sercos Interface
  • CC-Link
  • Ethernet Powerlink
  • Sercos the automation bus
  • CompoNet
  • Modbus
  • SmartWire-DT
  • DeviceNet
  • IO-Link
  • Ethernet
  • Profibus
  • Varan

The following are most common fieldbus protocols explained:

  1. Profibus: Profibus is a widely adopted fieldbus protocol that supports both process automation (Profibus PA) and factory automation (Profibus DP). It offers high-speed communication, robustness, and flexibility, making it suitable for various industrial applications.
  2. Modbus: Modbus is a simple and open fieldbus protocol commonly used for connecting devices in a supervisory control and data acquisition (SCADA) system. It operates over serial communication and is known for its ease of implementation and cost-effectiveness.
  3. Foundation Fieldbus: Foundation Fieldbus is a digital, bi-directional, and multi-drop fieldbus protocol designed for process automation. It enables advanced control strategies, device diagnostics, and asset management, enhancing the efficiency and reliability of industrial processes.
  4. DeviceNet: DeviceNet is a fieldbus protocol primarily used for connecting industrial devices on a factory floor. It provides plug-and-play capabilities, allowing for easy integration of devices from different manufacturers.

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How Fieldbus Protocol Works

Fieldbus protocols operate on a master-slave communication model. The master device, such as a programmable logic controller (PLC) or a distributed control system (DCS), controls and coordinates the communication with the slave devices. The master device sends commands and receives data from the slave devices, enabling real-time monitoring and control.

Fieldbus protocols utilize a variety of communication media, including twisted-pair copper cables, fiber optics, or wireless connections. They employ different data transmission methods, such as time division multiplexing (TDM) or token passing, to ensure reliable and deterministic communication.

Connecting industrial serial devices can be quick, easy, and reliable with DusunIoT fieldbus gateway CDGW-006. Their smart functionality makes connecting your Modbus and PROFIBUS devices effortless.

Levels of a Fieldbus System

The various levels of a Fieldbus system must be understood in order to fully comprehend the fundamentals of a Fieldbus network and what Fieldbus is. There are basically four different levels that can make up a Fieldbus system. These levels are listed from least to most complex, and include a sensor bus network, a device bus network, a control bus network, and an enterprise bus network.

Sensor Bus Networks

A sensor bus network is the most fundamental component of a Fieldbus system designed for industrial applications. Multiple basic field devices, such as limit switches or level optical sensors, are connected to one network cable at this level. This level can transmit output signals from the controller over one cable to alarms, indicator lamps, or other actuator devices

Device Bus Network

While the sensor bus network operates on a smaller scale, the device bus network operates on a much larger scale. In addition to connecting equipment to motor control centers and variable speed drives, which make it easier to control individual network elements, this level also connects a lot of sensors and actuators together.

Control Bus Network

Control bus networks are the most complex networks utilized on the factory floor. Here, high-level data communication takes place. Programmable logic controllers (PLCs) and smart instruments are linked to human interface panels (HIPs) within these networks to enable full configuration and control of every instrument on the network.

Enterprise Bus Networks

The enterprise bus network, also called the information level network, links all computers and divisions together. The Fieldbus system’s most intricate and expansive network level is at this level. It is primarily computer-driven and involves extensive data collection, file transfers, and computer monitoring.

Different Fieldbus Network Topology

A fieldbus for industry can have a wide variety of arrangements for its components. Some of the most common types of industrial Fieldbus configurations include:

  • Ring: Each node in a ring topology is directly connected to two additional nodes—one on each side—to create a continuous, circular pathway for data to travel through.
  • Line: Also known as a daisy chain or bus topology, a line topology entails nodes that are all linked to a host computer one by one in a line.
  • Star: In a star topology, each device is connected to a central hub or node, which serves as a conduit for data transmission.
  • Tree: A tree or branch topology is a hybrid topology that consists of star networks that are connected by line topologies, resembling the branches of a tree.

Why Use Fieldbus Protocol

Fieldbus protocols enable faster and more efficient communication between devices, reducing response times and improving system performance.It provides a standardized framework, ensuring compatibility and interoperability between devices from different manufacturers. 

This simplifies system integration and allows for flexible expansion and modification. Fieldbus protocols allow for the integration of multiple devices on a single communication network, reducing the need for extensive wiring. This leads to cost savings, easier maintenance, and improved system scalability.

Fieldbus provides significant benefits for all types of industrial operations:

  • Control-in-the-field (device to device communication)
  • Closed-loop control (sensor feedback)
  • Reduced cabling (multiple devices per cable)
  • Reduced hardware (via VirtualMarshalling™)
  • Reduced system footprint (fewer I/O cards, devices, cable tray, etc.)
  • Reduced device count (multivariable devices)
  • Faster commissioning (compared to traditional approaches)
  • Tighter control constraints (via control in the field)
  • Enhanced diagnostics (via higher power availability and signal status)
  • Easy online upgrades (bumpless transfer allows upgrades from the comfort of your work console)


Fieldbus Protocol for industrial Applications

Fieldbus protocols find applications in various industries, including manufacturing, oil and gas, chemical processing, power generation, and more. Some common applications include:

  • Process Control: Fieldbus protocols enable precise control and monitoring of industrial processes, ensuring optimal performance and efficiency.
  • Device Diagnostics: Fieldbus protocols provide advanced diagnostic capabilities, allowing for proactive maintenance and troubleshooting of field devices.
  • Asset Management: Fieldbus protocols facilitate asset management by providing real-time data on device status, performance, and health, enabling predictive maintenance and reducing downtime.
  • Factory Automation: Fieldbus protocols play a vital role in connecting and controlling devices in factory automation systems, improving productivity and flexibility.


Fieldbus protocols have revolutionized industrial communication by providing standardized, efficient, and reliable connectivity between devices. With their diverse types, robustness, and advanced features, fieldbus protocols have become an integral part of modern industrial automation, enabling enhanced control, diagnostics, and asset management.

DusunIoT CDGW-006 fieldbus gateway is designed for industrial automation factories using different networks. It can realize the rapid connection of different industrial networks (Modbus, BACnet, DMX512, BNP3, etc.) and perform protocol conversion to facilitate continuous information flow throughout the factory. CDGW-006 Modbus BACnet gateway converter employs MediaTek MT7628 as its core along with a wide range of interfaces, including one WAN network port, two LAN network ports, two COM RS485 ports, and one USB 2.0 interface, in order to ensure fast, convenient and dependable connection of industrial serial devices in the factory. 

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