Technical data

5.7 Communication with FMS (CP 5431 FMS)
FMS communication is discussed in detail in Volume 2 (CP 5431 FMS).
Here, there is only a overview of the services available. For further
information about the model and configuring, refer to Volume 2 (CP 5431
FMS).
SINEC L2-FMS (Fieldbus Messaging Specification), is the version for
application with the completely standardized PROFIBUS.
The interface of the CPs to FMS can be divided into the following:
– Cyclic interface (CI)
– Application layer interface (ALI)
➣ Data transfer with cyclic communication (using CI)
This type of communication is always suitable when values only need to
be written or read cyclically. The jobs to be processed cyclically are
specified during configuration. Only the variable values are exchanged
between the PLC and CP. The CP creates the appropriate FMS-PDUs
automatically.
➣ Data exchange with acyclic communication (using ALI)
☞
This type of communication is advantageous when the
services used and the time they are used is controlled by the
user program. Job buffers containing a job description and
possibly also data are exchanged between the PLC and CP.
The PDU is created based on the content of the job buffer.
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B8976060/02 Selecting the Type of Communication
5 - 11 Volume 1