Siemens SIMATIC ET 200AL, System Manual

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Functions
5.5 Intelligent DP slaves (I-slaves)
PROFIBUS with STEP 7 V13
Function Manual, 12/2014, A5E03775446-AC
79
Advantages of configurations with I-slaves
The I-slave offers the following advantages:
●
Simple coupling of CPUs with PROFIBUS interface
● Real-time communication between CPUs and PROFIBUS interface
● Distributed processing
A complex automation task can be divided into smaller units/subprocesses. This results
in manageable processes which lead to simplified subtasks.
● Relieving the DP master by distributing the computing capacity to I-devices
● Lower communication load by processing process data locally
● Separating subprocesses
Complicated, widely distributed and extensive processes can be subdivided into several
subprocesses with manageable interfaces by using I-slaves. These subprocesses can be
stored in individual STEP 7 projects if necessary, which can later be merged to form one
master project.
● Separating STEP 7 projects
Creators and users of an I-device can have completely separated STEP 7 projects. The
GSD file together with the configuration of the transfer areas of the I-slave form the
interface between the STEP 7 projects. This allows coupling to standard DP masters via
a standardized interface.
● Know-how protection
Plant units can now only be delivered with a GSD file and the configuration of the transfer
areas instead of with a STEP 7 project for the I-slave interface description. This means
that you no longer have to disclose the user program know-how.