PROFIBUS DP overview
PROFIBUS manual
Version FELD-V2002.02
Page 11
4 PROFIBUS
4.1 Overview
PROFIBUS was developed as an open fieldbus. It was standardized in the
German standard DIN 19 245 and was later incorporated in the European
standard EN 50 170, Vol. 2. PROFIBUS is a medium for pure data transfer,
like the RS232 standard for instance.
There are two different types of communication
•
Cyclical services PROFIBUS DP (Distributed
Peripheral)
•
Acyclical services PROFIBUS DPV1 (optional services)
PROFIBUS DP (Distributed Peripheral) is a PROFIBUS version designed to
satisfy the requirements of high-speed, efficient data transfer between a
controller (PLC / PC) and remote peripheral devices.
Physical design: Similar to RS 485
A DP system normally consists of one master and up to 126 slaves with the
use of repeaters. In systems employing multiple masters, each master has its
own permanently assigned slaves.
Master:
A DP master exchanges data with the slaves via PROFIBUS DP and
monitors the bus. It transfers the data between the higher-level controller and
the remote peripheral devices.
Slave:
The DP slaves form the link to the measurement equipment. They
condition the input data from the measurement application for communication
with the master, and condition the output data (control signals) from the
master for forwarding to the measurement electronics
The PROFIBUS uses the master-slave technique for data transfer. The master
reads the input data cyclically from the slaves and writes the output data to the
slaves.
PROFIBUS DP features:
•
Transfer rate of 9.6 kbaud to 12 Mbaud
•
Fast response times and high interference immunity
•
Master and slave diagnostics
•
Individual slaves can fail or be switched off without interfering with
bus operation.
•
The whole bus configuration is saved in the master.
•
Each slave has a manufacturer-specific ID assigned by the PNO.
•
The slaves are specified by the device description data (GSD file).
This file is imported into the configuration software, simplifying
slave configuration.