In order to connect a Gatekeeper-X with the CU42E0 an AVUTEC IO extender is necessary.
The IO extender has to be placed in the back of the Gatekeeper.

Gatekeeper-X junction box with green connector for the IO extender

Wiring diagram IO extender and CU42E0
The IO extender is wired to the Salto CU42E0 control unit as follows
IO extender |
Salto CU42E0 |
|---|---|
Data 0 (D0) |
positive terminal on input 5 |
Data 1 (D1) |
positive terminal on input 6 |
GND |
negative terminal on input 5 |
GND |
negative terminal on input 6 |