Explanations relating to some Profibus devices

The abbreviation DP stands for "decentralized periphery". In PROFIBUS-DP systems, a master device, e.g. a PLC or a PC, usually communicates with many slave devices, e.g. inputs, outputs or drives. Only the master device may actively access the bus and send unsolicited telegrams. A slave device only sends telegrams if it has been requested to do so by a master device.

PROFIBUS-DP allows a high degree of flexibility for system configuration, with up to 126 devices on one bus. It is possible to configure mono-master systems or multi-master systems. System configuration involves the following tasks: defining the number of stations; assigning station addresses to the I/O addresses; specifying parameters for the bus; and setting the format for diagnosis messages. Data consistency for the I/O data must be maintained during system configuration.