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SECTION 5
Detection Options
!WARNING Use of Fixed Blanking and Floating Blanking will make an MS4800 system
less sensitive to objects in the detection zone. Improper use of these features
can result in severe injury to personnel. Fixed Blanking may require a hard
barrier guard. Fixed Blanking and Floating Blanking may require an increase
in the safety distance. Read the following section carefully.
5-1 Fixed Blanking
Fixed Blanking allows a system to blank optical beams and record the exact
pattern. A system can record and store a single pattern. The protected zone's
object detection is then based on the stored pattern. All obstructed optical
beams recorded during the selection must remain blocked and all clear
beams recorded during the selection must remain clear for the system to
enter or remain in the MACHINE RUN state.
A Fixed Blanking pattern may consist of more than one Fixed Blanked area.
Individual Fixed Blanked areas must be separated by at least one beam that
is always clear. A Fixed Blanking area may not crossover between "flexible"
segment boundaries.
Each Fixed Blanked area has a size and positional tolerance of ±1 beam to
allow for slight position variance and only the two beams on the edges of the
blanked area are allowed to vary. Because of this position tolerance, a reduc-
tion of the optical resolution takes place on the border area of Fixed Blanking
patterns. This reduction comprises two beams.
Tolerance effect of Fixed Blanked area on Resolution
Note The tolerance does not reduce the resolution of the entire light curtain, only
the ends of Fixed Blanked Areas. The user must consider the increased reso-
lution of the two beams at the ends of each Fixed Blanked Area.
Fixed Blanking Area
Obstruction
Additional Hard Guarding
Light Curtain Light Curtain
Detection Zone
Standard Resolution Effective Resolution at Ends of Fixed Blanked Areas
14 mm 34 mm
30 mm 60 mm
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