PROFIBUS – Process Field Bus

PROFIBUS is a fieldbus communication standard in the automation technology. The universal fieldbus is mainly used in manu­facturing-, process- and building auto­mation and has been standar­dized in IEC 61158 and IEC 61784. The so-called line topology is used for the PROFIBUS. The max­imum number of BUS part­ic­i­pants is limited to 126 and the individual BUS segments are divided into 32 part­ic­i­pants. Repeaters amplify the signal between the in­di­vidual segments. The PROFIBUS fieldbus is a master/slave system.

The master, usually only one in the system, sends data as an active participant according to its cycle. In addition, it requests data from passive participants, the so-called slaves, cyc­li­cally. The slaves, such as IO modules or drives, only ac­know­ledge or forward process data to the master and there­fore have no access to the bus. In principle, several masters can also be connected to a PROFIBUS field­bus. Fixed slaves are then assigned to the masters and the access of the two masters to the bus is synchronized via a token. Up to 244 bytes of data can be transferred per bus user.