Technical data

Description of the Architecture
Introduction to PROFIBUS on Industrial PC
14
C79000-G8976-C068
3.3 PROFIBUS
PROFIBUS is
•
the network for the cell and field area of the medium performance
range within the open, heterogeneous SIMATIC NET
communications system intended primarily for an industrial
environment.
•
a powerful communications system for low-cost applications. It
provides all the known advantages of a bus system and meets all
the requirements for flexible, cost-effective networking of
programmable logic controllers and computers in an industrial
environment.
Known under the name PROFIBUS, PROFIBUS is based on the
standard specified in EN 50 170 and is based on the ISO/OSI
reference model. By meeting the requirements of EN 50 170,
PROFIBUS provides the “openness” required for attaching components
from other vendors that comply with the standard.
PROFIBUS (Figure 3.3) is based on the ISO/OSI reference model, but
does not implement all seven layers. For reasons of performance and
to reduce costs, only layers 1 (Physical Layer / RS485) and 2 (Data
Link Layer / FDL) for the physical bus characteristics and access
techniques and layer 7 (Application Layer) as the user interface are
implemented. The attachment of layer 7 to layer 2 is controlled by the
lower layer interface (LLI). This provides all the required layer 3 to 6
functions.
7b
7a
6
5
4
3
2
1
empty
FDL (Fieldbus Data Link)
RS 485
LLI (Lower Layer Interface)
FMS
empty
DP
Transport
S7
homogeneous expansions
Network
user interfaces
Figure 3.3 The PROFIBUS Architecture
Area of Application
of PROFIBUS
PROFIBUS
The Protocol
Profile of
PROFIBUS
Architecture of
PROFIBUS