PROFIBUS is a manufacturer-independent field bus standard for applications in manufacturing, process and building automation. Profibus technology is described in fixed terms in DIN 19245 as a German standard and in EN 50170 / IEC 61158 as an international standard.

It specifies the technical and functional properties of a serial bus system. The PROFIBUS standard is thus available to every provider of automation product. PROFIBUS distinguishes between master and slave.

The masters determine thedata communication on the bus. A master can send messages without an external request if it has access rights to the bus (token). The slaves are peripheral devices. Typical slaves are I/O devices, valves, motors and transmitters. They have no bus access rights. They can only confirm received messages or send a message on the requestof the master. Slaves are passive devices on the PROFIBUS. PROFIBUS is composed of three types of protocol, each of which is used for different tasks. Of course, devices with all three protocols can communicate with each other in a complex system by means of a PROFIBUS network.The three types of protocols are: PROFIBUS FMS, DP, PA.

Only the two protocol types DP and PA today are important for process automation and are supported within the 800xA System developed by ABB