BECKHOFF TwinSAFE - Manual (Page 21)

Circuit examples
Application Guide TwinSAFE 19
2.3 ESTOP function variant 3 (Category 4, PL e)
The emergency stop button is connected via two break contacts to an EL1904 safe input terminal. The
testing of the two signals is activated. These signals are checked for discrepancy. The restart and the
feedback signal are wired to standard terminals and are transferred to TwinSAFE via the standard PLC.
Furthermore, the output of the ESTOP function block and the feedback signal are wired to an EDM block.
This checks that the feedback signal assumes the opposing state of the ESTOP output within the set
time.
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.
2.3.1 Parameters of the safe input and output terminals
EL1904
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