BECKHOFF TwinSAFE - Manual (Page 82)

Circuit examples
80 Application Guide TwinSAFE
2.13 Laser scanner (Category 3, PL e)
The laser scanner has two OSSD outputs (Output Signal Switching Device), which are wired to safe
inputs of an EL1904. The testing of the inputs is not active, since the OSSD outputs carry out their own
test. Furthermore, the signals are checked for discrepancy (200 ms). The feedback loop is read via a safe
input. Testing is active for this 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.
2.13.1 Parameters of the safe input and output terminals
EL1904 (applies to all EL1904 used)
Parameter Value
Sensor test channel 1 active No
Sensor test channel 2 active No
Sensor test channel 3 active Yes
Sensor test channel 4 active Yes
Logic channel 1 and 2 OSSD any pulse repetition
Logic channel 3 and 4 Single Logic
EL2904
Parameter Value
Current measurement active Yes
Output test pulses active Yes