Rockwell Automation Allen-Bradley 140M, Руководство пользователя

Страница: 29 / 192

Rockwell Automation Publication 450L-UM001F-EN-P - March 2022 29
Chapter 4 Safety Function
Teach-in Fixed Blanking
Beams are taught to ignore up to four fixed objects in the sensing field. The
blanked fixtures or objects must remain in the sensing field or the 450L-E
safety light curtain enters a Fault state (OSSDs off).
Theoretically, the maximum number that can be blanked can nearly reach the
whole length of the protective field. At minimum, the first two active lenses at
the connection end or the last two active lenses at the cascading end must be
unblocked (
Table 4 on page 29 ).
The fixed Teach-in blanking mode of operation is activated through DIP
switch settings that are on following plug-ins:
• 450L-APR-BL-5 ( Table 25 on page 56 ) or
• 450L-APR-MU-8 ( Table 26 on page 56 )
With Teach-in blanking, the beams to be blanked are taught by activating the
optical teach button, which is located near the hand symbol on the 450L-E
safety light curtain front window (see
Figure 14 on page 31 ), in a specific
sequence (see Figure 15 on page 31 ) while the object is in the 450L-E safety light
curtain sensing field. The safety light curtain fixed blanking mode of operation
is not activated until the teach procedure is complete.
The fixed blanking mode of operation is always monitored. If any part or all
blanked objects are removed from the protective field, the OSSD outputs of the
450L-E safety light curtain go to the OFF state and the Rx stick displays a
blanking error (see
Table 56 on page 104 ).
Due to vibrations often present in industrial applications, the number of
physically interrupted beams is allowed to be one less than the specified
number of beams. A local adjustment of this tolerance value -1 is not possible
with DIP switches.
If the fixed blanked object only blocks one beam, the tolerance value is zero.
This value means that a minimum of one beam has to be blocked, there is no
tolerance.
The 450L-E safety light curtain can perform fixed blanking of one or more
adjacent beams. At minimum, one of the two synchronization beams
(
Figure 10 on page 22 ) must be unblocked before and during the Teach-in
procedure.
A teach-in error occurs if one of the cases that are described in Table 4 (see
Figure 13 for illustration) happens:
IMPORTANT Blanked areas can require an additional risk analysis. If no mechanical
or other guarding is used to restrict access to the hazard, the blanked
area must be considered in the calculation of the safety distance.
Table 4 - Teach-in Errors and Behavior
Case Description Behavior
1
More than four independent objects
are in the protective field
In this case, the first four interrupted objects that start from
the connection plug-in are taught, all other objects are not
taught. As a result, the OSSDs stay in the OFF condition as long
as the additional objects are in the protective field.
2
The beams at top and bottom are
simultaneously blocked
In this case, the teach-in command is ignored and the 450L-E
safety light curtain continues operating with the previously
taught objects.
3
One object was moving during teach-
in
In this case, the teach-in command is completed, but the error
indication at the end of the teach-in process warns the user
that the taught limits can cause sporadic OSSD switching.