21
SICK MSL
8 007 653/09-04-01 Technical Description • MSL © SICK AG • Safety Systems • Germany • All rights reserved
7.3.3 Input: External Device
Monitoring (EDM)
The EDM monitors the switching
elements (e. g. contacters) which
are driven by the sensor outputs.
The EDM is activated whenever the
light beam is interrupted before the
machine restarts and its consequent
hazardous motion. The outputs of
the light barrier and switching
elements are active HIGH for an
uninterrupted light beam.
When operating with EDM the
switching element contacts to be
monitored are connected to the
EDM input (
fig. 23).
EDM expects the contacts to be in
their rest position (+ 24 V) and only
then enables the outputs OSSD 1
and OSSD 2 (active HIGH for
uninterrupted light beam).
Electrically, this means that both
break contacts (k 1, k 2) must close
when the switching elements (K 1,
K 2) reach their rest position due to
an interrupted light beam.
7.3.4 Input: Restart switch
(RES)
When operating with restart inhibit
(
chapter 6.2
), a make contact is
connected b 24 V and
the restart switch input (
fig. 24).
If the light beam is unobstructed,
the yellow LED on the receiver
flashes to indicate that the Restart
switch must be activated. After the
restart switch has been pressed
and then released again, the sensor
switches the outputs OSSD 1 and
OSSD 2 high (active), and the
green LED on the receiver lights
up.
Fig. 23: Schematic for restart switch and contacts with EDM
RES
EDM
OSSD1
OSSD2
k1
k2
K1
K2
+ 24 V
0 V
1
5
6
3
4
2
RES
5
4,7 K
+ 24 V
Fig. 24: Connection of the restart switch to
the receiver unit or to the MSLZ
The EDM switches the OSSDs off again ...
... if no reaction from the switching elements is determined
within 300 ms (dynamic EDM).
The contacts k 1 and k 2 must then be off. If this is not the
case, the outputs switch off again and the red LED on the
receiver unit lights up.
When operating with Restart Inhibit, it is necessary to press the
Restart Inhibit button (yellow LED flashes).
When operating without Restart Inhibit, the light beam must be
interrupted and enabled. The request to do this is indicated by
the continuously lit yellow LED on the receiver unit.
