User Documentation

4 System description of safe power-feed modules | Operation with and without test pulses
19u-remote IP20 modules for functional safety manual 1484600000/07/11.2020
4.6 Operation with and without test pulses
The safe input circuits are designed to connect passive dual
channel switching devices. Each input channel is provided
with pulsed voltage the test pulses of which are analysed.
Therefore the highest safety levels can be achieved (see tech-
nical data).
1
2
3
4
1
2
3
4
S11 / S31
S12 / S32
S21 / S41
S22 / S42
S11 / S31
S12 / S32
S21 / S41
S22 / S42
+24 V DC
Safety relay
Sensor
Exemplary operation with test pulses
The safe power-feed module UR20-PF-O-2DI-DELAY-SIL
might also be operated without test pulses. This is mandato-
ry whenever an external device gernerating own test pulses
is connected.
When using switching devices generating own
test pulses please regard that low level with a
duration of more than 2ms will be detected as an
opening of the safety circuit.
1
1
2
3
4
1
4
2
3
4
+24 V DC
S11 / S31
S12 / S32
S21 / S41
S22 / S42
GND
...
1
2
3
4
+24 V DC
S11 / S31
S12 / S32
S21 / S41
S22 / S42
Safety relay
with
OSSD
outputs
Exemplary operation of the UR20-PF-O-2DI-DELAY-SIL without test pulses
Test pulses can be enabled or disabled using the DIP-switch-
es of the module.