BECKHOFF TwinSAFE - Manual (Page 77)

Circuit examples
Application Guide TwinSAFE 75
2.12 Two-hand control (Category 4, PL e)
The two-hand buttons each consist of a combination of break and make contacts on safe inputs of an
EL1904. The testing of the inputs is active and the signals are tested for discrepancy (200 ms). In
addition, the synchronous actuation of the two buttons is activated with a monitoring time of 500 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.
2.12.1 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