In accordance with the FOUNDATION Fieldbus guideline (refer to section Standards and
Approvals (Page 77)), each process variable is assigned a status byte that specifies the status
of the process variable.
When an FF device fails, the associated input data, including the status byte, is reset in the
user data frame of the bus link. Then the corresponding information is entered into the
diagnostic frame.
On recovery of the FF device, corresponding information is entered in the diagnostic frame.
Virtually simultaneously, the valid input data of the FF device is made available again in the
user data frame of the bus link. The associated status byte displays the valid data.
Note
The status data of the FF devices is evaluated immediately by the
SIMATIC PCS 7 drivers and
diagnostic blocks and is then made available on the operator and maintenance stations.
3.2
Active field distributor for connecting FF segments
Active field distributors (Active Field Distributor and Active Field Splitter)
Active field distributors can be operated on a bus link. FF devices such as measuring
instruments, sensors, and actuators can be connected to these field distributors.
You can find example configurations with active field distributors in the following sections:
● Section "Single-channel connection of the Compact FF Link (Page 21)"
● Section "Redundant connection of the Compact FF Link (Page 21)"
You can find types of active field distributors released for PCS 7 in the catalog overview
Process control system PCS 7, released modules.
Active Field Splitter
An active field splitter offers the following functions:
● Coupler redundancy on an FF segment, for redundant connections to the automation
system
● Connecting FF devices to a non-redundant FF segment
Active Field Distributor
An active field distributor offers the following functions:
● FF device connection
● Decoupling the FF device from an FF segment
● Automatic bus termination
● Extension and replacement of field devices during operation of the FF segment
Description of the components
3.2 Active field distributor for connecting FF segments
Compact FF Link
Operating Instructions, 03/2015, A5E35651552-AA
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