Siemens SIMATIC S7 System Manual page 450

Communication
8.6 RS485
After you select the "System Block" dialog, you perform the following steps:
1. Select the network address and baud rate for the RS485 port.
2. Download the system block to the CPU.
Note
Freeport protocol baud rates are set using SM memory.
450
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART