LINK Systems Max Presence Sensing Device - Manual (Page 38)

Link Lite Black Max Section 4 - Operating Instructions
4-5
NOTE! The Black Max always gives a
stop signal unless the blanking mode
selector switch is in the RUN position.
Always remove the key from the switch
when blanking mode selection is complete.
Figure 4.3: VARIBLANK mode selected.
When VARIBLANK mode is selected, it
requires that any two (not necessarily side
by side) sensors in the main Black Max
unit sensing field be blocked before the
Black Max will signal the machine or
production system to stop hazardous
action. This mode is sometimes useful for
feeding strip stock or material that is thin
enough that it will only block one sensor at
a time through the sensing field of the
Black Max so that it doesn't stop the
machine. Of course, since its possible that
a person will also now have to block two
sensors to stop hazardous machine action,
VARIBLANK has the effect of increasing
minimum object sensitivity, M.O.S., by the
space between any two adjacent sensors
(.75 inches for most main Black Max
units). This is the case if the material that
blocks one sensor doesn't stay in place at
all times and extend all the way across the
Black Max sensing field. You must follow
the safe blanking requirements of section
4.2.4.
4.2.2 FIXED BLANKING
Fixed blanking is the turning off of specific
sensor channels in the main Black Max
sensing field to allow fixed objects that are
necessary to the production system to
extend through the sensing field without
preventing the machine or production
system from operating. No more than
seven (7) sensors can be fixed blanked on
a standard Black Max unit. Any
combination of seven sensor channels can
be blanked.
If the object that requires sensors to be
blanked is perfectly stationary in the
sensing field, you may use the blanking
mode selector switch to select FIXED
BLANKING mode by turning the key to
the SELECT position and releasing the key
to the PROGRAM position until only the
FIXED BLANKING mode indicator lights
are on, as shown in Figure 4.4.
Figure 4.4: FIXED BLANKING selected.
After you have selected FIXED
BLANKING return the blanking mode
selector switch to the RUN position and
remove the key. Any receiver sensor (but
only up to seven in total number) that is
blocked from receiving its signal from the
transmitter by a stationary object will be
automatically blanked when you turn the
blanking mode selector to the RUN
position, and will remain blanked as long
as the object is in place. The blanked
sensors will be indicated by the channel
indicator lights (located behind the red
acrylic lens in the front of the receiver).
The indicator light for each blanked
channel will blink, as opposed to being
OFF when there is no obstruction or ON
when there is an obstruction but the sensor
is not blanked.