27
5.4.1.3 Calculating Safety Clearance
Safety clearance is calculated with the same method used for a non-blanked safety light curtain. Mechanical
curtains must be utilized in order to assure that fix blanked beams cannot be penetrated.
5.4.2 Floating Blanking
In certain applications, objects protrude continuously into the safety field, although their positions cannot be
precisely pinpointed. Objects of this sort may include cables which are located within the safety field for
technical reasons, or tools which pass through the safety field. The “floating blanking” function is intended
for use in these applications.
Differentiation is made between two types of floating blanking:
• Floating blanking
• Auto floating blanking
5.4.2.1 Principle
Up to 3 objects can pass through the safety field without causing the safety output
to switch. The beams which are obstructed by the objects are adapted to the re-
spective size of the object, and are muted accordingly.
There is a limit to the number of beams which can be blanked (see table 1 on page
36).
The safety output is not switched until additional beams above and beyond the
blanked beams have been interrupted, for example if someone reaches into the
safety field
Prerequisites for use:
• The operating mode “Floating Blanking” can only be parameterized over the serial interface. (vide operat-
ing instructions B-wsafe)
•
Testing must be performed in order to determine whether or not floating blanking can be used,
where-by all possible object arrangements (practical experience) have to be tested.
• The “restart inhibit” and “contactor monitoring” functions can be activated as required in the floating
blanking operating mode.
•
Safety clearance is influenced by floating blanking
è
section 5.4.2.2
• The first beam must not be blanked
