BECKHOFF TwinSAFE - Manual (Page 27)

Circuit examples
Application Guide TwinSAFE 25
2.4 ESTOP function variant 4 (Category 4, PL e)
The emergency stop button with two break contacts, the restart and the feedback loop are connected to
safe channels of an EL1904 input terminal. The testing of the signals is activated. The two emergency
stop signals are tested for discrepancy. 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.
2.4.1 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