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•
Closing or locking the movable physical guard must not trigger the automatic
starting of a hazardous machine function. This must occur by means of a separate
start command.
•
The safety switch tests the OSSDs at regular intervals. To do this, the safety switch
switches each OSSD briefly (for max. 300 µs) to the OFF state and checks whether
this channel is voltage-free during this time. Make sure that the machine’s control
does not react to these test pulses and the machine does not switch off.
4.4.1
OSSDs
Overview
You can integrate the safety component directly into the machine controller via the
safety outputs (OSSDs). The OSSDs indicate the ON state with the HIGH signal level
(non-isolated). The OFF state is indicated with the LOW signal level.
Downstream control elements must evaluate the output signals of the safety compo‐
nent in such a way that the dangerous state of the machine is safely ended. Depending
on the safety concept, the signal is analyzed by, e.g., safety relays or a safety controller.
Isolated connection of OSSD1 and OSSD2
•
It must be possible to electrically influence the control of the machine.
•
The electrical control of the machine must meet the requirements of IEC 60204-1.
•
When using a safety controller, different signal levels of both OSSDs must be
detected depending on applicable national regulations or required reliability of the
safety function. The maximum discrepancy time tolerated by the controller must
be selected according to the application
•
The OSSD1 and OSSD2 output signals must not be connected to each other.
•
In the machine controller, the signals of both OSSDs must be processed sepa‐
rately.
Avoiding any potential difference between the load and safety component
If you connect loads to the output signal switching devices (switching outputs) that
then also switch if controlled with negative voltage (e.g., electro-mechanical contactor
without reverse polarity protection diode), you must connect the 0 V connections of
these loads and those of the corresponding protective device separately and also
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 safety component.
Figure 8: No potential difference between the load and safety component
PROJECT PLANNING
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8020562/2022-07-07 | SICK
O P E R A T I N G I N S T R U C T I O N S | flexLock
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Subject to change without notice