In the realm of industrial automation and precise object detection, the photoelectric switch stands as a cornerstone technology. Among the diverse models available, the RL28-8-H-2000-IR/105/110 photoelectric switch represents a specific and capable solution designed for demanding applications. This article provides a detailed, factual overview of this device, its operational principles, key specifications, and typical use cases, steering clear of marketing hyperbole to focus on technical clarity.
At its core, the RL28-8-H-2000-IR/105/110 is a self-contained, modulated infrared sensor. The designation itself offers insights into its characteristics. The "RL28" typically refers to the housing style and form factor—a cylindrical, threaded barrel design, often with an M18 thread, which is a standard for easy mounting in industrial panels and machinery. The "8" likely indicates the sensing distance. In this context, "2000" often specifies a 2-meter (2000mm) operating range, which is a substantial distance for a diffuse or retro-reflective photoelectric sensor, enabling detection of objects from afar. The "IR" confirms the use of an infrared light source, which is less susceptible to ambient light interference compared to visible light. The "105/110" portion commonly relates to the electrical connection and output configuration, such as cable type, length, or connector style, and often denotes a 3-wire DC configuration (e.g., PNP or NPN transistor output).
The device operates on the principle of modulated light beam interruption or reflection. It emits a pulsating infrared beam. In a through-beam setup, a separate receiver detects this beam; an object breaking the beam triggers the switch's output. In a retro-reflective mode, the switch emits light towards a dedicated reflector, and the output activates when an object interrupts the return beam to the built-in receiver. The "H" in the model number may indicate a particular feature set, such as enhanced environmental resistance or a specific housing material. The modulated infrared technology is key to its reliability. By pulsing the light at a specific frequency, the sensor's internal circuitry can distinguish its own signal from constant ambient light (like factory lighting), dramatically reducing false triggers and ensuring stable operation in variable lighting conditions.
Key technical specifications define its application boundaries. A standard model like this typically operates on a 10-30V DC supply, making it compatible with common industrial control voltages like 12V or 24V DC. The output is usually a solid-state transistor (PNP or NPN) capable of switching small control currents, which then interface with programmable logic controllers (PLCs), relays, or other control systems. The 2-meter sensing range is a significant feature, allowing for flexible installation where objects need to be detected at a distance without physical contact. The housing is generally rated at IP67 or similar, indicating a high degree of protection against dust ingress and temporary immersion in water, which is crucial for washdown environments in food processing or outdoor applications.
The applications for the RL28-8-H-2000-IR/105/110 photoelectric switch are vast within industrial settings. Its long range and robust construction make it ideal for object presence detection on conveyor belts, such as verifying the passage of boxes, bottles, or parts. It can be used for counting items, controlling automated processes based on object position, or as a safety interlock to detect when a guard door is open. In packaging machinery, it ensures materials are present before a sealing or labeling operation begins. In material handling, it can detect the level of bulk goods in a container or the position of a pallet on a transport line. The infrared light source allows it to function reliably even where visible light sensors might fail due to colored objects or shiny surfaces that could confuse standard sensors.
Installation and alignment are straightforward but critical. For retro-reflective use, the sensor must be correctly aligned with its companion reflector across the detection path. The long 2-meter range provides a generous margin for alignment. Wiring follows standard practice: connecting the brown wire (typically +V), blue wire (0V or common), and the black wire (switched output signal) to the corresponding terminals on the power supply and controller. Users must ensure the electrical characteristics (sourcing PNP vs. sinking NPN) match the requirements of the connected control system to avoid damage or malfunction.
In summary, the RL28-8-H-2000-IR/105/110 photoelectric switch is a versatile, long-range sensing component engineered for industrial automation. Its modulated infrared technology, substantial sensing distance, and durable housing make it a reliable choice for non-contact detection tasks where accuracy and environmental resilience are paramount. Understanding its specifications and operating principle allows engineers and technicians to deploy it effectively in countless automation scenarios, from simple presence checks to complex sequential control systems.
