Solutions For The Fieldbus - Siemens SIMATIC PCS 7 Function Manual

Fault-tolerant Solutions in PCS 7
3.3 Solutions for communication
3.3.5

Solutions for the fieldbus

3.3.5.1 Redundant PROFIBUS DP
Functionality
The field bus is used for data exchange between the automation system (AS) and the
distributed I/O. PROFIBUS DP (distributed peripheral)-- the field bus standard for
manufacturing and process automation--is used. PROFIBUS DP includes the specifications
for the following elements:
● Physical bus characteristics
● Access method
● User protocol
● User interface
PROFIBUS DP is suitable for fast, cyclic data exchange with field devices. It is used to connect
distributed I/O, for example, ET 200M, with very fast response times.
It is often advantageous to connect several DP master systems to an automation system in
order to increase the number of I/O components that can be connected. This also enables
segments to be formed, allowing individual production areas to operate independent of one
another.
Fault-tolerant communication solutions
The following fault-tolerant communication solutions are offered for PROFIBUS DP:
● Redundant PROFIBUS DP as an electrical network
● Redundant PROFIBUS DP with OLMs (optical network)
Configuration
The S7-400H fault-tolerant automation system features a DP master interface on each CPU
for connecting to PROFIBUS DP. The redundant PROFIBUS DP connects the redundant DP
master to the redundant interface modules of the distributed I/O.
The following figure shows an example for connecting redundant distributed I/O based on ET
200M to a redundant PROFIBUS DP.
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Fault-tolerant Process Control Systems (V8.0)
Function Manual, 03/2012, A5E02779471-02