Specifications

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Publication S117-CA001A-EN-P
Presence Sensing Safety Devices
Safety Light Curtains
2-11
Overview
GeneralPrinciples
2-Opto-electronics
Safety SwitchesOperator
Interface
LogicPower
R
Conveyorized muting
Muting sensors are typically used in pairs and depending upon the
sensor configuration and muting module, allow either uni-directional
or bi-directional travel of material through the safety light curtain.
Machine Conveyor
Material
Muting Lamp
MS2MS1
Muted LC1
LC2
Machine Conveyor
Material
Muting Lamp
MS4 MS3 MS2 MS1
LC
Muted LC1
MS2 MS1
LC
Muting lamp
GuardShield Perimeter Access Control (PAC)
Figure 4
 Optic heads (operate on 24V DC)—ordered as a pair
(transmitter/receiver) mounting brackets included
 Cables—separate 4-pin transmitter and 8-pin receiver
 Safety relay if EDM is not used
 Corner mirrors (for multiple side protection)
LC
Muting lamp
MS1
MS2
Figure 4: Two-sensor T-type with MSR42
Figure 3: Two-sensor L-type with MSR42
Figure 2: Four-sensor uni-directional muting
Figure 1: Two-sensor bi-directional muting
The muting sensors must be spaced appropriately from the safety
light curtain and each other in order to ensure that the sensors
cannot be interrupted by personnel, causing the activation of the
muting function.
A requirement of muting in machine applications is for indication
that the muting function is activated. This is typically accomplished
by the use of a muting lamp. The various muting modules offered by
Rockwell Automation have an output for the connection of a muting
lamp.
Four-sensor muting for this particular muting module in Figure 2
allows a single direction of travel. A particular sequence is also
required in this configuration; muting sensor 1 must be interrupted
first followed by muting sensor 2 and then the safety light curtain,
then muting sensor 3 and finally muting sensor 4. It is necessary
with this particular muting module to have the light curtain’s sensing
field interrupted within 3 seconds of muting sensor two being
interrupted. Also, the material must block muting sensor 3 and
muting sensor 4 before clearing muting sensors 1 and 2 or the
muting function is overridden and the safety light curtain would
become active causing a nuisance shutdown of the machine if the
material is within the light curtain sensing field.
An interruption of the safety light curtain sensing field would cause
the machine or the hazardous motion to be turned off. The muting
cycle is completed when the material clears muting sensor 4.
The Allen-Bradley Guardmaster GuardShield PAC safety light curtain
system is a two-box design. This means the safety light curtain
does not need a separate controller to operate in a guard-only
mode with manual reset. Therefore, the safety outputs of the light
curtain (OSSDs) can be connected directly to any safety relay that
will accept PNP inputs.
The following are some common configurations of light curtain
systems. The numbers on the drawing indicate the ordering steps to
follow to ensure that a complete system is specified.
Components required for a multiple-beam PAC system, see
Figure 3: