Siemens SIMATIC S7-1500 Automation System System Manual page 67

Use of the potential bridges at digital modules
With the delivered potential bridges, for digital modules with a maximum rated voltage of
24 V DC, you can bridge the terminals for the voltage supply and thus reduce the wiring
effort. The bridges are used to connect respectively the facing terminals 9 and 29, 10 and
30, 19 and 39 as well as 20 and 40.
Reference
Further information on wiring the inputs and outputs can be found in the manuals for the
I/O modules.
S7-1500 Automation System
System Manual, 01/2013, A5E03461182-01
6.8 Front connector for the I/O modules
Wiring
67