BECKHOFF TwinSAFE - Manual (Page 70)

Circuit examples
68 Application Guide TwinSAFE
2.11 Protective door function with tumbler (Category 4, PL e)
The protective door has two contacts, S1 ‘door closed’ and S2 ‘door closed and locked’, which are wired
to safe inputs of an EL1904. The testing of the inputs is active. Checking of the signals for discrepancy
cannot take place, because there is no temporal relationship between the signals. The feedback loop and
the restart signal are read via a safe input. The testing of the inputs is active. 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.
The tumbler is switched via 2 safe inputs in which testing is active. Testing and current measurement is
active on the safe output for the tumbler.
CLOSED
OPEN
K1
K2
Unlock
Lock
Restart
S1
S2
Logical connection in
the EL6900
K1 K2
2.11.1 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