Rockwell Automation Publication 450L-UM001D-EN-P - December 2019 35
Safety Function Chapter 4
Reduced Resolution (Object
Number Limited)
Reduced resolution is a type of blanking without monitoring whether the beams
are interrupted. The comparable blanking function with monitoring is called
floating blanking. So floating blanking and reduced resolution have similar
functionality, the difference according to the standard IEC 61496 is the object
monitoring.
Reduced resolution is always specified in combination with a beam number
There are different types of reduced resolution:
• All blanked beams must be adjacent. The maximum size of the object is
equal to the beam value. This type is only good for one single object
(reduced resolution, single object).
• Blanked beams can be, but do not have to be adjacent. The sum of the size
of all object in the protective field is not larger than the beam value
(reduced resolution, multiple objects, object number limited).
• Blanked beams can be, but do not have to be adjacent. The size of each
object in the protective field is not larger than the beam value (reduced
resolution, multiple objects, object number unlimited).
The reduced resolution that can be activated with a DIP switch in a 450L-E
safety light curtain refers to the definition (b) multiple objects, object number
limited.
The reduced resolution mode of operation is activated through DIP switch
settings that are on the following plug-ins:
• 450L-APR-BL-5 (Table 23 on page 62
) or
• 450L-APR-MU-8 (Table 24 on page 62
)
Reduced resolution of one beam or reduced resolution of two beams allows one
or two beams that are located anywhere in the protective field to be blanked out,
for instance, blocked beams ignored and the 450L-E safety light curtain remains
with OSSD outputs active. Reduced resolution allows an object to float in (move
within, or in and out of ) the 450L-E safety light curtain protective field without
causing the light curtain outputs to change to the OFF state. For details, see
Table 7 on pa ge 36
and Table 8 on page 37.
For reduced resolution with object number limited, the maximum number of
blanked objects is equal to the beam number (see Table 6 on pag e 36
).
If activated by the DIP switch the reduced resolution is active over the entire
protective field, except the zones already taught with another blanking type.
IMPORTANT The blanking modes that can be activated with the DIP switches in a 450L-E
safety light curtain system is equal to the blanking modes that can be activated
in a 440L safety light curtain system.
IMPORTANT With reduced resolution activated, protective field holes that are left and/or
right of the protective field can occur. This occurrence means at times when
no object is blocking the protective field, there is a danger that the operator
can reach through the protective field without deactivating the machine.
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