Siemens Sinamics S120 Manual page 536

DC link components
8.3 Braking Module Booksize Compact
Note
The digital inputs DI are isolated and are referenced to M_DI (X21.5 and X21.6).
The reference point of the d igital outputs DO is the ground GND of the 24 V supply.
The connections for the temperature switches (X22.1 and X22.2) must not be assigned for
"braking resistor without a thermostatic switch" mode for the Braking Module to work.
Braking resistor with thermostatic switch connected to a Braking Module Booksize Compact
Figure 8-8 Connection example for Braking Module Booksize Compact and braking resistor with a
thermostatic switch
536
Booksize Power Units
Manual, (GH2), 04/2014, 6SL3097-4AC00-0BP6