Siemens Simatic S7-1500R System Manual page 92

Procedure
Proceed as follows to set up the supply through the CPU and system power supply:
1. In STEP 7, open the "Properties" tab for the CPU. Select "System power supply" in the
navigation.
2. Select the option "Connection to supply voltage L+".
Figure 3-23
Infeed via system power supply only
You can also feed the required power into the backplane bus using only a system power
supply. In this case, the CPU is supplied from the backplane bus rather than with 24 V DC.
In this case, the system power supply must be inserted to the left of the R/H-CPU in slot 0.
In general, you can use a system power supply with AC or DC infeed for the configuration.
Procedure
To set up infeed only via the system power supply, follow these steps:
1. In STEP 7, open the "Properties" tab for the CPU. Select "System power supply" in the
navigation.
2. Select the option "No connection to supply voltage L+".
Figure 3-24
Note
If you select the option "No connection to supply voltage L+", the power required for the R/H
CPU is supplied through the system power supply only. If you then compile the hardware
configuration in STEP 7, the warning "Power segment undersupplied" appears. This warning
has no effect on the functioning of the user program or of the redundant system.
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
Supply voltage via the CPU and system power supply
No supply to the backplane bus through the CPU
Application planning
3.7 Use of a system power supply
91