Safety Light Curtains

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Overview

GuardShield™

Introduction

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.

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.)

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

The standard GuardShield safety light curtain has DIP-switches located in both the transmitter and receiver endcaps. The DIP-switches are accessible through a hinged door that is secured to the endcap with a security screw.

The transmitter DIP-switches provide for the configuration and activation of Beam Coding and Machine Test Signal.

The receiver DIP-switches provide for configuration of all of the GuardShield safety light curtain's modes of operation.