Operating principle
● The Compact FF Link is a DPV1 slave on the higher-level DP master system and acts as
a proxy for the nodes connected to the lower-level bus system (FF devices).
A corresponding DP master is required for use of the Compact FF Link. If necessary, the
operating mode for the DP master being used can be selected in the Object Properties in
HW Config. This must be "DPV1".
● PROFIBUS DP and the FF segment are decoupled from one another:
– Physically (galvanically)
– In terms of communication
- In terms of protocol
- Temporally
● Together with the connected FF devices, the Compact FF Link forms an independent, lower-
level bus system (FF segment).
● Within the FF segment, the Compact FF Link, as an FF Link Master, controls the distributed
communication deterministically using the LAS. Some FF devices can perform process
control functions within the FF segment. This functionality is referred to as Control in the
Field (CiF).
● The CiF functionality is independent of any connection to the DP master system. A loss of
the connection to the DP master system has no effect on the CiF functionality on the FF
segment.
Information for redundant operation
● A bus link with increased availability of the FF segment is obtained by a redundant
configuration with two Compact FF Links.
● Both Compact FF Links have the same configuration information, the same parameter
assignment, and the same input data from the FF bus. Which of the two Compact FF Links
is active on the FF bus depends solely on the corresponding command from the higher-
level DP master. Only the active Compact FF Link sends cyclic output data to the FF bus
(Send request to FF devices).
● The acyclic data is independent of the cyclical data.
● If the active Compact FF Link fails, there is a bumpless changeover of the active channel.
Note
The redundant configuration with two Compact FF Links requires the connection to a redundant
automation system (SIMATIC S7-400H).
User data of the Compact FF Link
The DP user data frame of the Compact FF Link is dependent on the number of configured
FF devices. It comprises the data blocks of the configured FF devices arranged one after the
other. The data blocks are sorted in ascending order according to FF address.
Description of the components
3.1 Compact FF Link
Compact FF Link
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Operating Instructions, 03/2015, A5E35651552-AA