Siemens SIMATIC S7-1500 System Manual page 43

Procedure
To set up infeed only via the system power supply, follow these steps:
1. Open the "Properties" tab of the CPU/interface module in STEP 7 and select the "System
power supply" in the navigation.
2. Select the option "No connection to supply voltage L+".
Figure 3-8
Automation system
System Manual, 09/2016, A5E03461182-AD
No infeed into the backplane bus by means of the CPU/interface module
Application planning
3.2 System and load power supply
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