What is Profibus?

Profibus can be described as the international fieldbus communications standard for linking process control and plant automation modules. Profibus uses a single multi-drop cable instead of running individual cables from a main controller to each sensor and actuator, in order to connect all devices. High-speed, bi-directional, serial messaging is used to transfer information. The manner in which Profibus operates holds a number of benefits. Not only does it offer savings on cabling costs when compared with older methods, but it also allows for simple linking of devices from different vendors and reduces installation, commissioning, fault-finding, and associated plant downtime costs.

Different Profibus Versions

There are two different versions of Profibus, effectively known as Profibus DP and Profibus PA.

Profibus DP

Profibus DP (Decentralized Peripherals) is used to operate sensors and actuators via a centralized controller in production (factory) automation applications. The main focus here is on the many standard diagnostic options.

Profibus PA

Profibus PA (Process Automation) is used to monitor measuring equipment via a process control system in process automation applications. This Profibus version is designed for use in explosion/hazardous areas. The physical layer, which is the cable, conforms to IEC 61158-2, which allows power to be delivered over the bus to field instruments, while limiting current flows so that explosive conditions are not created, even if a malfunction does occur. The number of devices attached to a Profibus PA segment is limited by this feature. Profibus PA uses the same protocol as Profibus DP, and can be linked to a Profibus DP network using a coupler device. The much faster Profibus DP act as a backbone network for transmitting process signals to the controller. The subsequent result is that Profibus DP and Profibus PA can work tightly together, especially in hybrid applications where process and factory automation networks operate side by side.