Siemens SINAMICS S120 Manual page 386

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8.15 K90, Control Unit CU320-2 PROFIBUS
NOTICE
An open input is interpreted as "low".
To enable the digital inputs (DI) to function, terminal M1 must be connected.
This is achieved by:
1. Providing the ground reference of the digital inputs, or
2. a jumper to terminal M.
Notice! This removes the electrical isolation for these digital inputs.
Note
If a momentary interruption in the voltage occurs in the 24 V supply, the digital outputs are
deactivated until the interruption has been rectified.
386
Cabinet Modules
Manual, (GH5), 05/2010, A5E03263538A