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: It is possible to attain a Category 3 system by connecting the GuardShield OSSDs directly to two safety contactors and connecting and configuring the EDM mode of operation in the GuardShield's receiver.) The Allen-Bradley GuardMaster safety light curtain is a two box safety light curtain, consisting of a non matched transmitter and receiver pair. Any GuardShield transmitter of same protective height and resolution will work with any receiver of same protective height and resolution. The GuardShield safety light curtain has two transistor type, PNP safety outputs. These outputs may be connected to a safety relay module or directly to the primary control element of a machine. The GuardShield also has an auxiliary non safety output which can be connected to a PLC for status of the OSSDs, to a stack light or to control an infeed motor, etc. The GuardShield requires separate Transmitter and Receiver cables. The Transmitter cable utilizes a 4-pin micro quick-disconnect connector and is offered in lengths from 2 meters to 30 meters. The receiver cable has an 8-pin micro quick-disconnect connector and is also offered in lengths from 2 meters to 30 meters. The Allen-Bradley GuardMaster GuardShield is a two box, Type 4 light curtain with dip switch selectable operating modes.