Siemens Simatic PCS 7 Function Manual page 84

High availability solutions in PCS 7
4.3 Solutions for communication
High availability communication solutions
The following communication solutions are offered to prevent a possible failure:
● Ring redundancy with the AFD (Active Field Distributor)
● Coupler redundancy with the AFS (Active Field Splitter)
The DP/PA coupler can be used stand-alone or in the PA-Link .
Note
Mixed configurations
You can connect only one redundant DP/PA coupler pair per PA-Link . In mixed configurations,
you can operate up to 3 additional non-redundant DP/PA couplers. The coupler pair (FDC
157-0 DP/PA coupler) should be installed for redundant operation in the last two slots of the
ET 200 station.
Connecting the high availability PROFIBUS PA to PROFIBUS DP
You can connect a high availability PROFIBUS PA to the PROFIBUS DP. The following
variants can be realized:
● Redundant connection to the redundant PROFIBUS DP
– The redundant PA-Link is the transition to the high availability PROFIBUS PA.
● Connection to a single PROFIBUS DP PROFIBUS DP
– A DP/PA-Link with redundant coupler pair is the transition to the high availability
– A coupler pair FDC 157 is the transition to the high availability PROFIBUS PA.
We recommend the following configuration limits in PCS 7 when connecting PA devices using
AFD or AFS :
● In the case of ring redundancy (high availability connection):
– In the interest of increased availability, connect a maximum of 4 field devices (one field
– You can connect a total of 31 field devices.
● In the case of coupler redundancy:
– 1 AFS connected to a redundant DP/PA coupler
– Connect field devices via AFD (max. 8 AFD).
– In the interest of increased availability, connect a maximum of 4 field devices (one field
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(2 x interface module and 2 x DP/PA coupler)
PROFIBUS PA.
(1 x interface module and 2 x DP/PA coupler)
(2 x DP/PA coupler directly to PROFIBUS DP)
device per branch line) to an active field distributor AFD (maximum of 8 AFD to a
redundant DP/PA coupler).
device per branch line) to an active field distributor AFD (maximum of 8 AFD to an AFS).
High Availability Process Control Systems (V9.0)
Function Manual, 05/2017, A5E39221836-AA