•
Prevent the formation of a potential difference between the load and the protec‐
tive device. If you connect loads to the OSSDs (safety outputs) that then also
switch if controlled with negative voltage (e.g., electro-mechanical contactor with‐
out reverse polarity protection diode), you must connect the 0 V connections of
these loads and those of the corresponding protective device individually and
directly to the same 0 V terminal strip. In the event of a fault, this is the only way to
ensure that there can be no potential difference between the 0 V connections of
the loads and those of the corresponding protective device.
O
S
SD A
O
S
SD B
O
S
SD A
O
S
SD B
Figure 32: No potential difference between load and protective device
DANGER
Hazard due to lack of effectiveness of the protective device
In the case of non-compliance, it is possible that the dangerous state of the machine
may not be stopped or not stopped in a timely manner.
Downstream contactors must be positively guided and monitored depending on appli‐
cable national regulations or required reliability of the safety function.
b
Make sure that downstream contactors are monitored (external device monitoring,
EDM).
•
Each OSSD pair in the safety laser scanner is equipped with an internal EDM.
Requirements for the electrical control of the machine
The OSSDs are short-circuit protected to 24 V DC and 0 V. When the protective field is
clear, the OSSDs signal the ON state with the HIGH signal level (non-isolated). If there
are objects in the protective field or there is a device fault, the OSSDs signal the OFF
state with the LOW signal level.
4.5.5
Control inputs
Overview
The safety laser scanner is equipped with control inputs:
•
The control inputs accept signals for switching between different monitoring cases.
•
Static control inputs are used for information about machine status.
When switching between monitoring cases, bear in mind that a person may already be
in the protective field when switching takes place. So, you must make sure that the
monitoring case is switched at the right time. Only switching in time (namely before the
danger arises for the person at this location) ensures protection,
.
PROJECT PLANNING
4
8023152/1G5N/2022-06-28 | SICK
O P E R A T I N G I N S T R U C T I O N S | outdoorScan3 Core I/O
51
Subject to change without notice