Installation, Operation and Maintenance Manual
MAN 618-42 Rev. 7 November 2021
PROFIBUS DP Description 5
Section 5: PROFIBUS DP Description
Section 5: PROFIBUS DP Description
PROFIBUS is a vendor-independent, open eld bus standard used in a wide range of application
in process automation. Vendor independence and openness are ensured by the international
standards EN 50170 and EN 50254. The DP communication prole is designed for data exchange at
the eld level. The central controllers (as PLC) communicate via serial connection with eld devices
(as sensors and actuators). Data exchange is mainly cyclic. The central controller (called Master)
cyclically reads the input information from the eld devices (called Slaves) and cyclically writes the
output information to the slaves. In addition, PROFIBUS DP provides communication services for
parameterization, alarm handling and monitoring of intelligent eld devices. The maximum number
of Master and Slave devices in a bus segment is 32 without repeaters. With repeaters, the number can
be extended to 126. The maximum cable length depends on the speed of transmission. Higher is the
speed, shorter is the length. For instance, with baud rate 93.75 kb/s, the max cable length is 1,200 m
without repeaters.
Mono-master or multi-master system conguration can be provided. Bus access is controlled by token
passing procedure between masters and master-slave procedure (polling) between master and slaves.
Types of devices:
DP Master Class 1 (DPM 1): This is the central controller that cyclically exchange information
with the eld devices. Typical devices are PLC or PC.
DP Master Class 2 (DPM 2): These devices are necessary for commissioning, maintenance
and diagnostics.
Slave: Field device such transmitters, actuators, drives, etc.
Figure 2 below shows a PROFIBUS DP conguration with two Master devices and different Slave devices.
Figure 2
2000 actuators
Logical token ring between master devices
Master
devices
Slave devices
General Drive Transmitter
PLC PC
