Allen-Bradley 42MRL-5000 Photoelectric Head

Allen-Bradley 42MRL-5000 Photoelectric Head is the emitter (photohead) component of Rockwell Automation’s Series 5000 through-beam PhotoSwitchR sensors. As part of the Green Line family, the 42MRL-5000 sends an infrared beam to a matching receiver (for example, 42MRR-5000) to detect when the beam is interrupted by a target. This configuration is commonly used for long-range object detection on conveyors, packaging lines, and other manufacturing processes where a remote sensing pair provides reliable presence/absence information. The head features an infrared LED emitter and offers a light/dark selectable mode, allowing you to choose whether a detected event corresponds to light-on or dark-on signaling in your control logic. With a stated sensing distance from 25.4 mm (1 in) up to 171 mm (6.7 in), the 42MRL-5000 supports a compact to mid-range through-beam arrangement without requiring a local receiver at the head itself. The device provides a fast 5 ms response time, enabling quick feedback for high-speed production lines and precise timing in automation sequences. In practice, the 42MRL-5000 is deployed wherever a discrete, durable photoelectric transmitter is required to establish a defined sensing zone and trigger a compatible receiver’s output, fitting neatly into the Series 5000 ecosystem for streamlined wiring and compatibility with standard Rockwell Automation controllers and wiring schemes.