Siemens SIMATIC PCS 7 Function Manual page 77

Figure 3-2
Transmission rate
You have two interfacing options for the gateway between PROFIBUS DP and PROFIBUS
PA. These result in different transmission rates on PROFIBUS DP.
● If you connect the DP/PA couplers via a DP/PA-Link , a transmission rate of up to 12 Mbps
is possible on the PROFIBUS DP.
● If you connect the DP/PA couplers directly, the transmission rate on PROFIBUS DP is 45.45
Kbps.
● The transmission speed on the PROFIBUS PA is 31.25 Kbps.
Availability - redundant interfacing
In a redundant system, we recommend that you implement the connection to the PROFIBUS
DP redundantly (redundant IM 153-2).
If a PA bus cable, an IM 153-2 or a DP/PA coupler fails, the communication connection to the
field devices is retained. The AFD or AFS automatically switches the connection to the
available signal path.
Fault-tolerant Process Control Systems (V8.1)
Function Manual, 11/2014, A5E34878832-AA
Connection to a single PROFIBUS DP
Fault-tolerant Solutions in PCS 7
3.3 Solutions for communication
77