Fieldbus is a group of protocols used in the industrial field. Fieldbus protocols are standardized as IEC61158. Fieldbus operates on a network that allows various topologies such as star, branch, ring. Before fieldbus, industrial control systems were connected using RS-232 serial communication. However, in serial communication, only two devices could be connected to each other. Today, we can connect multiple devices together thanks to fieldbus. Fieldbus connections are connected to a single port to which we can connect many field devices, and then to the PLC controller. However, fieldbus is not a standalone connection type. It is used to indicate a group of protocols.
This group includes ControlNet, Profibus, HART, Modbus, EtherCAT, CIP and more. The primary benefit of fieldbus is for field-connected devices. For example, we have several field devices. These devices are far from our computer. Switches, motors, lights, etc. The devices are connected to a data block, then to the field distribution device and finally to the PLC device. Connections to fieldbus components are made with a single cable, except for the field device. In this way, cable savings are achieved in the fieldbus protocol. Our control system must have a communication module to communicate with field devices.
For example: Profibus will need a profibus module. But this does not mean that all protocols are specific to a particular brand. Some protocols cannot work well with others. For example, ControlNet cannot be integrated into the Siemens processor.