Siemens SIMATIC S7-1500 System Manual page 32

Application planning
3.2 System and load power supply
Procedure
To set up the supply by means of the CPU/interface module and 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 "Connection to supply voltage L+".
Figure 3-7
Infeed via system power supply only
As a further possibility you can feed the required power into the backplane bus using only a
system power supply. In this case, the CPU/interface module is not supplied with 24 V DC,
and draws its supply from the backplane bus. Insert the system power supply to the left of
the CPU/interface module.
In general you can use system power supplies with AC or DC infeed for the configuration. If
you want to supply the first power segment directly with 230 V AC, an infeed via only one
system power supply makes sense, for example, if no 24 V DC supply voltage is available.
Procedure
To set up the supply by means of 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
32
Supply voltage via the CPU/interface module and system power supply
No infeed into the backplane bus by means of the CPU/interface module
Automation system
System Manual, 12/2014, A5E03461182-AC