BECKHOFF TwinSAFE - Manual (Page 57)

Circuit examples
Application Guide TwinSAFE 55
2.9 Protective door function variant 2 (Category 4, PL e)
The protective door uses a combination of break and make contacts on the safe inputs of an EL1904. The
testing of the inputs is active and the signals are tested for discrepancy (200 ms). The feedback loop is
read in via a safe input. The contactors K1 and K2 are connected in parallel to the safe output. Current
measurement and testing of the output are active for this circuit.
2.9.1 Parameters of the safe input and output terminals
EL1904 (applies to all EL1904 used)
Parameter Value
Sensor test channel 1 active Yes
Sensor test channel 2 active Yes
Sensor test channel 3 active Yes
Sensor test channel 4 active Yes
Logic channel 1 and 2 Single Logic
Logic channel 3 and 4 Single Logic
EL2904
Parameter Value
Current measurement active Yes
Output test pulses active Yes