Allen-Bradley 445L PAC GuardShield Type 4 Safe 4 Safety Light Curtain

The GuardShield Safe 4 safety light curtain consists of a nonmatched pair of optic units, i.e., transmitter and receiver with the same protected height and resolution. The transmitter and receiver operate on +24V DC. The maximum distance between transmitter and receiver is referred to as the protective field width or range. The protective field height is the distance between the first and last beam in the device. The transmitter emits sequential pulses of infrared light which are received and processed by the GuardShield Safe 4 receiver. The synchronization of the timing of the emission and reception of infrared light pulses is accomplished optically by the first beam adjacent to the GuardShield Safe 4 status LEDs. This beam is referred to as the synchronization beam. Because the GuardShield Safe 4 transmitter and receiver are optically synchronized, no electrical connection is required between the transmitter and receiver.

The GuardShield Safe 4 receiver has two safety outputs, Output Signal Switching Devices (OSSDs). When the GuardShield Safe 4 transmitter and receiver are properly powered and aligned, all OSSDs are current sourcing +24V DC with a switching capacity of 300 mA. The two safety OSSDs are cross monitored and shortcircuit protected. Interruption of the sensing field causes the receiver to switch the sourced current OFF (0V DC).