38 Rockwell Automation Publication 450L-UM001D-EN-P - December 2019
Chapter 4 Safety Function
Especially critical for the resolutions are the borders between two adjacent
blanking zones. Table 9 on pag e 3 7
provides the largest resolution for a complete
light curtain system for different DIP switch settings.
For blanking in the case of cascading, see Cascading and Blanking on page 52
.
Muting
The cascading feature is only available for the 450L-E safety light curtain. To
enable the muting functionality, the receiver plug-in 450L-APR-MU-8 must be
installed.
Certain applications in practice require that the protective field of the 450L-E
safety light curtain is muted automatically without the safety outputs switching
off. A typical example of such an application is a conveyor belt. It is possible to
transport the goods on a pallet through the protective field without stopping the
pallet movement.
Muting is the temporary automatic suspension of the protective function of a
safeguarding device like a light curtain. The muting function allows the transport
of material through a light curtain without stopping a conveyor. To distinguish
between material and persons, a certain sequence of events and timings are used.
Muting sensors are mounted in a certain pattern, and the material must pass by
the sensors and light curtain within specified time limits. If the muting sensor
sequence is incorrect or the timing parameters are violated, the safeguarding
device stops the conveyor. An override signal allows the movement of the
material through the light curtain after a violation.
The 450L-E safety light curtain has three distinct types of muting, where the
sequence and timing of signals that the light curtain monitors allows objects to
pass through the light curtain without shutting down the machine process. The
three available types are:
• Two sensors, T-type muting (bidirectional operation)
• Four sensors, T-type muting (bidirectional operation)
• Two sensors, L-type muting (unidirectional operation)
The two-sensor muting types can be connected at the connection plug-in (see
Figure 69 on page 104
) or at the cascading plug-in 450L-APC-IO-8 (see
Figure 75 on page 110
). The four-sensor muting type can only be connected at
the cascading plug-in 450L-APC-IO-8.
To activate the desired muting functionality, select the DIP switches of the
receiver plug-in 450L-APR-MU-8 according to Table 24 on page 62
and
Table 26 on page 63
.
IMPORTANT A detailed description about muting, muting restrictions and hints for the
installation are given in the standard IEC 62046. Additional hints are
mentioned in the attachment A7 of IEC 61496-1. The muting function, is
only allowed after a thorough safety analysis according to EN 13849-1 and
ISO EN 12100 is completed.
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