Specifications

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Publication S117-CA001A-EN-P
Presence Sensing Safety Devices
Safety Light Curtains
2-8
Overview
General Principles
2-Opto-electronics
Safety Switches Operator
Interface
Logic Power
R
GuardShield™
Introduction
Typical System Configuration
Components required for a "Guard only" system:
1. Optic heads (operate on 24V DC—ordered as a pair
(transmitter/receiver)
2. Cable—two required per pair—specify transmitter cable and
receiver cable
3. Mounting brackets—included
4. Safety Relay Module—optional (Note: A Category 3 system may
be possible by connecting the GuardShield OSSDs directly to
two safety contactors and connecting and configuring the EDM
mode of operation in the GuardShield receiver.)
1
2
3
4
Receiver
Interlock
Mode
Activation
Button
Fixed
Blanking
2 Beam
Floating
Blanking
(14 mm only)
Unused
Door Status
Switch
Guard Only
MPCE/EDM
1 Beam
Floating
Blanking
Beam
Coding
The Allen-Bradley Guardmaster GuardShield is offered as a Type 2
and a Type 4 POC safety light curtain as well as a Type 4 PAC
safety light curtain. The Type 4 POC GuardShield is offered in both
14 mm and 30 mm resolutions while the Type 2 is offered in 30 mm
resolution only. The GuardShield PAC is offered with multiple beam
configurations with varying beam spacings. All GuardShield family
safety light curtains meet the requirements of IEC/EN 61496.
POC safety light curtains are designed to detect the presence of an
opaque object of a minimum resolution. These devices are usually
positioned in front of the point of operation hazard, however, they
may also be used for perimeter guarding applications.
PAC safety light curtains are typically used as opto-electronic
fences or as whole body detection devices to detect personnel or
large objects when they pass through the sensing field. These PAC
safety light curtains are typically positioned around an area or in
front of a process entry or exit area.
The Allen-Bradley Guardmaster GuardShield is a two-box safety
light curtain, consisting of a nonmatched transmitter and receiver
pair. Any GuardShield transmitter of the same family (POC, PAC)
and same resolution will work with any receiver of the same family
and resolution. The synchronization between transmitter and
receiver is achieved optically. The first beam adjacent to the receiver
LEDs is the synchronization channel. This synchronization beam
cannot be blocked in a fixed or floating blanking application.
The GuardShield safety light curtain has two transistor type PNP
safety outputs, referred to as OSSDs (Output signal switching
devices). These outputs may be connected to a safety relay module
or directly to the primary control element of a machine if the EDM
connection within the GuardShield receiver is also connected and
configured.
The standard GuardShield receiver also has an auxiliary nonsafety
output which can be connected to a PLC for status of the OSSDs,
to a stack light for signaling or to control an in-feed motor, etc.
The standard GuardShield requires separate transmitter and receiver
cables. The transmitter cable utilizes a 4-pin micro quick-disconnect
(M12) connector and is offered in lengths from 2 meters to 30
meters. The receiver cable has an 8-pin micro quick-disconnect
(M12) connector and is also offered in lengths from 2 meters to 30
meters.
The Allen-Bradley Guardmaster GuardShield Type 4 is a two-box
light curtain with DIP switch selectable operating modes.
Receiver DIP Switch Functions or GuardShield Type 4 POC