Technical data

The ISO/OSI reference model is divided into 2 different areas:
➣
Transport-oriented layers: 1 - 4
➣
Application-oriented layers: 5 - 7
In SINEC L2/L2FO the lower layers 1 (physical layer) and 2 (data link layer)
comply with the PROFIBUS standard DIN 19245 Part 1. SINEC L2 supports
various transmission techniques (layer 1):
➣
RS-485 transmission technique (complying with the PROFIBUS
standard) /4/
➣
Fiber-optic transmission technique
The medium access control technique (layer 2) in SINEC L2/L2FO is a
hybrid technique operating according to the
➣
Token bus principle for "active stations"
and the
➣
Master-slave principle between "active" and "passive" stations.
Layer 2 provides the standardized FDL interface "Fieldbus Data Link" for
the higher layers. Frames can be processed on this interface with two
different priorities (high, low).
L2 transport as layer 4 provides functions such as segmentation, link
establishment and link termination.
Explanations of the layer 2 communication model for SIMATIC S5 are in
Chapter 3 of this manual (Volume 1) in Chapter 3.
Explanations of the FMS model for SIMATIC S5 are in Volume 2 of the
manual for the CP 5431 FMS.
Explanations of the TF communications model for SIMATIC S5 are in
Volume 2 of the manual for the CP 5430 TF.
B8976060/02 System Overview
2 - 9 Volume 1