Weidmuller SAI Active Universal Pro Series, Manual

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SAI Pro
2.2 PROFIBUS-DP
PROFIBUS
PROFIBUS (PROcess Field BUS) is a part of the
international standards IEC 61158 and IEC 61784.
Physically, PROFIBUS is either an electrical network
based on a shielded, two conductor cable or an opti-
cal network based on a fibre optics cable.
PROFIBUS-DP (DP = Decentralised Periphery) is a
special application for automating factory production.
System
A typical PROFIBUS-DP system is made up of
•
at least one PLC or industrial PC (master) operat-
ing as a control system
•
various field devices, which can be digital or ana-
logue I/O devices, AC or DC drives, magnetic or
pneumatic valves, frequency converters, starters,
operating and display devices (slaves)
Data transfer
Data exchange within the system is carried out by
means of cyclic polling. The master establishes
communications with one slave at a time, makes
data available and/or requests data. The slave being
addressed responds immediately to the request for
data. Once completed, this procedure is repeated
with the other slave devices. This is a continuous
cyclic process.
GSD files (device database files)
The GSD file is the obligatory "ID card" of each and
every PROFIBUS device. It contains the characteris-
tic data of the device, details about its communica-
tion capabilities as well as further information such
as diagnostic values. All GSD files for the SAI Active
Universal range of SAI distributors can be
downloaded from Weidmueller’s website at:
http://www.weidmueller.com/54266/Downloads/Soft
ware/SAI-Active-Data/cw_index.aspx?newsid=
For more information, please refer to
Chapter “Commissioning the PROFIBUS-
DP”.
Figure 3 Basic PROFIBUS system configuration
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