Introduction To The Profibus Dp Protocol; Profibus Dp Network; Profibus Dp Protocol Versions; Device Types In A Profibus Dp Network - WEG CFW500 User Manual

1 INTRODUCTION TO THE PROFIBUS DP PROTOCOL

A general overview of Profibus DP protocol, describing the main characteristics and functions, are presented
next.
1.1

PROFIBUS DP NETWORK

The term Profibus is used to describe a digital communication system that can be used in several application
areas. It is an open and standardized system, defined by the IEC 61158 and IEC 61784 standards, which
comprises from the used physical medium to data profiles for certain sets of equipments. In this system, the DP
communication protocol was developed with the purpose of allowing a fast, cyclic and deterministic
communication between masters and slaves.
Among the several communication technologies that can be used in this system, the Profibus DP technology
describes a solution that, typically, is composed by the DP protocol, RS485 transmission medium and
application profiles, used mainly in applications and equipments with emphasis in manufacturing automation.
Nowadays, there is an organization named Profibus International, responsible for keeping, updating and
publishing the Profibus technology among users and members. More information regarding the technology, as
well as the complete protocol specification can be obtained with this organization or with one of the
regional associations or competence centers associated to the Profibus International.
1.2

PROFIBUS DP PROTOCOL VERSIONS

The Profibus DP protocol defines a series of functions for exchanging data between master and slave. The set
of functions can be divided in different functional levels, in the following versions:
DP-V0: It is the first version of the protocol, which mainly defines functions to perform cyclic data exchange

between master and slave.
DP-V1: It is an extension of the functions defined in the first version; it defines particularly how to perform

the exchange of acyclic data between master and slave, besides the cyclic data.
DP-V2: It defines a set of advanced functions such as communication between slaves and isochronous

communication mode.
The CFW500 frequency inverter supports the services of the DP-V0 and DP-V1 versions.
1.3

DEVICE TYPES IN A PROFIBUS DP NETWORK

Three different types of equipment are specified in a Profibus network:
Slaves: They are passive stations in the network, which only answer to the requests made by the master.

Class 1 Master: It is responsible for the cyclic data exchange. Typically represented by the PLC, or process

or plant control software.
Class 2 Master: It allows the communication in the Profibus DP network through acyclic messages.

Typically represented by an engineering or configuration tool used for network commissioning or
maintenance.
The CFW500 frequency inverter operates as a slave in the Profibus DP network.
1.4

PHYSICAL LAYER

There are different network transmission types to allow communication in a Profibus network, each one with
suitable features according to the demands of different application types. The main transmission modes are:
RS485: this is the most used transmission type for Profibus network. It provides high transmission rates,

simple installation and low cost.
MBP: this is specified mainly for applications in chemical and petrochemical industries, for communication

in safety areas. The transmission rate is defined at 31.25 kbit/s with the possibility of feeding the devices
from the communication bus.
Optical Fiber: this is used mainly in applications where high electromagnetic interference immunity and/or

great distances connections are required.
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.ctiautomation.net - Email: info@ctiautomation.net