A Fieldbus is a digital communication system used in automation and process control technology to network sensors, actuators, measuring devices, and controllers. It enables the exchange of measured values, status information, and control commands via a shared communication line, thereby replacing a large portion of traditional point-to-point wiring.
Fieldbus systems are used to transmit so-called Field Equipment – such as temperature, pressure, or flow sensors – are connected to higher-level control systems, PLCs, or automation devices. Actuators such as valves, drives, or switches can also be integrated into the communication network.
Data transmission follows clearly defined communication rules. In many traditional fieldbus systems, the Master-Slave Principle used. In this configuration, a master device controls data traffic and determines when individual participants are allowed to send or receive data. The connected slave devices respond to corresponding requests or commands from the master.
Standardized communication protocols specify the following:
- Who is permitted to communicate with (identifier or address)
- What data are transmitted (measurement values, status information, or commands)
- When the type of communication taking place (request, response, or cyclic transmission)
Thanks to these defined communication mechanisms, even large automation systems with many participants can be operated reliably and deterministically.
Examples of typical fieldbus protocols include:
- PROFIBUS
- CAN-Bus
- Modbus RTU
- DeviceNet
- CANopen
- INTERBUS
In modern measurement and data acquisition systems, fieldbuses are frequently used to collect measurement data from distributed areas of a plant and transmit it to central evaluation or control systems. They thus serve as an important interface between sensor technology, control technology, and industrial IT.
Advantages of fieldbus systems:
- Reduced wiring effort
- Easy integration of many devices
- High reliability and resistance to interference
- Centralized Diagnostic and Configuration Options
- Flexible scalability of systems
- Efficient Transmission of Measurement and Control Data
Significance for Measurement Technology
In industrial measurement and data acquisition, fieldbus systems enable a wide variety of sensors and measuring devices to be connected to central data acquisition or automation systems. This allows measured values to be efficiently recorded, processed, and used for monitoring, control, or analysis tasks.
Today, fieldbuses are among the most important communication standards in the automation and process industries and form the basis for numerous modern measurement and control solutions.