Siemens SIMATIC S7-1500 Function Manual page 336

Changing the HMI connection over to the device IP address
To permanently change the HMI connection over to the selected CPU, clear the check box
"Use the system IP address for switched communication" in the properties of the HMI
connection. The HMI connection then uses the device IP address of the PROFINET
interface. In the event of the failure of this CPU, then the HMI connection to this CPU
permanently fails.
Figure 13-9 Properties of the HMI connection
Note
Automatic setup of HMI connection
When you drag-and-drop a tag from the S7-1500R/H redundant system into an HMI screen
or into the HMI tag table, STEP 7 automatically sets up an HMI connection. This HMI
connection exists by default between the PROFINET interface of the HMI device and the
PROFINET interface X1 of the CPU with redundancy ID 1. The connection uses the
device IP address of the PROFINET interface X1.
You can change the HMI connection to a system IP address in the properties of the HMI
connection.
Communication
Function Manual, 11/2019, A5E03735815-AH
Communication with the redundant system S7-1500R/H
13.5 HMI communication with the redundant system S7-1500R/H
335