Siemens ST PCS 7 Manual De Usuario
Communication
PROFIBUS
Introduction
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Siemens ST PCS 7 · November 2007
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Overview
Communication at field level with PROFIBUS
Distributed peripherals such as remote I/O stations with their
I/O modules, transmitters, drives, valves or operator terminals
communicate with the automation systems (controllers) at field
level through a powerful real-time bus system. This communica-
tion is characterized by:
• Cyclic transmission of process data
• Acyclic transfer of interrupts, parameters and diagnostics
• Cyclic transmission of process data
• Acyclic transfer of interrupts, parameters and diagnostics
data
PROFIBUS is predestined for these tasks because it enables
high-speed communication with the intelligent distributed I/Os
by means of a communications protocol (PROFIBUS DP) as well
as communication and simultaneous power supply for transmit-
ters and actuators (PROFIBUS PA).
PROFIBUS is simple, rugged and reliable, can be expanded on-
PROFIBUS is simple, rugged and reliable, can be expanded on-
line by further distributed components, and can be used in both
standard environments and hazardous areas. It supports the co-
existence of field devices from different vendors on one line (in-
teroperability) as well as the vendor-independent exchangeabil-
ity of devices from one profile family.
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Benefits
SIMATIC PCS 7 utilizes the benefits of the PROFIBUS from start
to finish:
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Small planning and engineering overheads as well as low
commissioning costs
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Optimum distributed system structure with low hardware and
space requirements
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Significantly reduced overhead for wiring, jumpering, distribu-
tion, power supply and field mounting
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High-speed communication with high measurement accuracy
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Efficient engineering, interoperability and replaceability of de-
vices through vendor-independent device description
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Short commissioning times through short loop tests, easy pa-
rameterization and the elimination of calibration work
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Bidirectional communication and high amounts of information
permit enhanced diagnostics functions for fast fault locating
and troubleshooting
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Optimum life cycle management through processing and
evaluation of diagnostics and status information by an asset
management system
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Function
Users have numerous facilities for communication and line diag-
nostics, as well as for diagnostics of the intelligent field devices
connected. Furthermore, the PROFIBUS is fully integrated into
the global asset management of the SIMATIC PCS 7 process
control system.
In addition to all these properties, the following PROFIBUS func-
In addition to all these properties, the following PROFIBUS func-
tions are particularly relevant to process automation:
• Integration of previously installed HART devices
• Redundancy
• Safety-related communication with PROFIsafe up to SIL 3 ac-
• Integration of previously installed HART devices
• Redundancy
• Safety-related communication with PROFIsafe up to SIL 3 ac-
cording to IEC 61508
• Clock synchronization
• Time tagging
On account of its exceptional characteristics, PROFIBUS is now
• Time tagging
On account of its exceptional characteristics, PROFIBUS is now
established in all sectors of the production, process and hybrid
industries and has become the most successful open field bus
in the world.
PROFIBUS transmission systems
PROFIBUS DP
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RS 485: simple and low-cost electrical transmission system
based on shielded two-wire cable.
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RS 485-iS: intrinsically-safe electrical transmission system for
hazardous areas up to Ex zone 1, implemented using a
shielded two-wire cable with a transmission rate of 1.5 Mbit/s.
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Fiber-optic: optical transmission system with glass or plastic
fiber-optic cables, for fast transmission of large quantities of
data in environments with high interferences or for covering
long distances.
PROFIBUS PA
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MBP (Manchester Coded; Bus Powered): intrinsically-safe
transmission system which permits simultaneous transmission
of digital data and powering of the field devices on a single
two-wire cable. It is suitable for direct connection of devices in
environments up to Ex zone 1 or 21 and associated sen-
sors/actuators in environments up to Ex zone 0 or 20.
PROFIBUS DP
PROFIBUS PA
PROFIBUS DP
OLM OLM
Industrial Ethernet
RS 485-iS coupler
Long distances
with fiber-optic
with fiber-optic
DP/PA link
Automation system
Ex isolation
+ repeater
+ repeater
© Siemens AG 2007