46 Rockwell Automation Publication 450L-UM001D-EN-P - December 2019
Chapter 4 Safety Function
If the object stops in front of the first sensor and does not block the light curtain,
the mute timing error goes HI and the mute lamp flashes at 1 Hz. The OSSD
outputs remain ON, which allows you to reverse the conveyor and restart the
muting sequence.
Use the S3 muting signal to clear the errors. When S3 goes HI, it clears the mute
timing error, mute sequence error, and the muting error outputs.
Four-sensor Muting
The sensors and light curtain form the shape of an upside down T, when viewed
from the side. Two muting sensors (MS) are mounted on either side of the light
curtain (LC).
Figure 20 - Four-sensor Muting
The material can travel in either direction; breaking MS1 first and MS4 last or
breaking MS4 first and MS1 last. The muting lamp turns on and the light curtain
is muted after the second sensor is blocked. The object must be large enough to
interrupt all four sensors.
For connecting the muting sensors, see Table 42 on page 94
.
This muting mode is considered when the size and position of the pallet load is
irregular, or the size of the pallet is much smaller than the width of the conveyor.
This mode can require more space than the two sensor T-type with enable signal
muting mode.
Sensors two and three (closest to the light curtain) are mounted within 200mm
(7.87 in.) of the light curtain. This position makes it difficult for a person to
enter the dangerous zone undetected by preceding or following a load system into
the dangerous zone.
The distance between any two muting sensors must be greater than 250 mm
(9.84 in.) so that a person's leg cannot activate them simultaneously.
The distance between sensor MS1 and MS4 is such that a cylindrical object with
a diameter of 500 mm (19.68 in.) with its axis parallel to the protective field
cannot activate the muting function when moved in any point of the gate at any
speed up to 1.6 m/s (see IEC 62064).
Machine
2SM1SM4SM3SM
LC
Muting Lamp
Material
Muted LC
Conveyor
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