VISOLUX SLVA-4Kplus-2528 Photoelectric Sensor

The VISOLUX SLVA-4Kplus-2528 is a high-performance photoelectric sensor manufactured by Pepperl+Fuchs Elektronik GmbH under the Visolux brand. This sensor operates on 24V DC power and utilizes diffuse reflection sensing technology with background suppression, providing reliable object detection in industrial automation applications. The sensor is designed for precise detection of objects regardless of color, reflectivity, or background conditions.

Product Overview

The SLVA-4Kplus-2528 belongs to the Visolux 4Kplus series of photoelectric sensors, known for their robust construction and reliable performance in demanding industrial environments. The sensor features a compact housing that is suitable for installation in tight spaces. The diffuse reflection sensing principle with background suppression allows the sensor to detect objects within a defined sensing range while ignoring reflective surfaces or objects beyond the set distance. This capability is particularly valuable in applications where conveyors, machine frames, or other background elements could cause false triggering with standard photoelectric sensors. The sensor incorporates advanced optics and signal processing electronics that provide consistent detection regardless of target color, surface finish, or ambient light conditions.

Technical Specifications

The SLVA-4Kplus-2528 operates on a 24V DC power supply with a tolerance of ±10%. The nominal sensing range is adjustable up to 250 mm, with background suppression that effectively ignores objects beyond the set distance. The sensor uses a red LED light source with a wavelength of 660 nm, providing a visible sensing beam that aids in alignment and setup. The output is a PNP normally open configuration, switching up to 200 mA at 24V DC. The switching frequency is 500 Hz, allowing detection of fast-moving objects on high-speed production lines. The response time is 1 ms, providing rapid signal changes for precise timing applications. The sensor includes a status LED indicator that illuminates when an object is detected, simplifying troubleshooting and setup verification. The electrical connection is made via a 4-pin M12 connector, providing secure and reliable connectivity in industrial environments.

Sensing Principle and Background Suppression

The diffuse reflection with background suppression technology used in the SLVA-4Kplus-2528 employs a triangulation measurement principle. The sensor projects a beam of light toward the target area and measures the angle of the reflected light using a dual-element receiver or position-sensitive detector. Objects within the set sensing range produce reflected light at an angle that triggers the output, while objects beyond the range produce reflected light at a different angle that is ignored. This technique ensures that only objects at the desired distance are detected, regardless of the reflectivity of the background surface. The background suppression feature is adjustable using a potentiometer on the sensor, allowing users to set the cutoff distance precisely for their application. This adjustment capability makes the sensor suitable for detecting objects on conveyors with varying background distances, or for sensing parts through openings in machine guards.

Mechanical Design and Environmental Protection

The SLVA-4Kplus-2528 is housed in a rugged plastic enclosure rated IP67 for protection against dust and temporary immersion in water. The housing dimensions are approximately 50 mm in length, 15 mm in width, and 30 mm in height, making it compact enough for installation in space-constrained machinery. The sensor includes a 4-pin M12 male connector that provides both power and signal connections in a single waterproof interface. The front lens is made of PMMA acrylic, which resists scratching and provides excellent optical clarity. The sensor can be mounted using the two through-holes provided in the housing, accepting M3 screws for secure attachment. The operating temperature range is -25°C to +60°C, allowing use in cold storage facilities or warm manufacturing environments. The sensor is resistant to vibration and shock per IEC 60068-2-6 and IEC 60068-2-27 standards.

Adjustment and Configuration

The SLVA-4Kplus-2528 features a simple yet effective adjustment system. A 15-turn potentiometer accessible through a sealed opening allows precise setting of the sensing range from the minimum to the maximum 250 mm distance. The potentiometer provides fine adjustment capability, enabling users to set the detection threshold exactly where needed. The sensor includes a yellow LED output indicator that illuminates when an object is detected within the set range. During setup, users can place a target object at the desired detection distance and adjust the potentiometer until the LED just illuminates, then turn slightly further for reliable operation. The sensor also includes a green LED power indicator that shows when the device is properly powered. For applications requiring normally closed operation, the sensor can be configured by swapping the load connection or using an external relay.

Applications

The SLVA-4Kplus-2528 is suitable for a wide range of industrial sensing applications. Typical uses include presence detection on assembly lines where parts are presented at a known distance; height verification to ensure products are not stacked too high; level detection of opaque liquids or granular materials in clear containers; part ejection confirmation in stamping and molding machines; edge detection for web handling and winding applications; and positioning control in automated handling equipment. The sensor's background suppression capability makes it particularly valuable for detecting dark objects on shiny conveyors, sensing small parts against reflective machine surfaces, and detecting clear or transparent objects where standard sensors may fail. The sensor is also suitable for counting applications where objects pass through the sensing beam at high speed.

Electrical Connections and Wiring

The SLVA-4Kplus-2528 uses a standard 4-pin M12 connector for electrical connection. The pin assignment is as follows: Pin 1 (brown) connects to +24V DC power; Pin 2 (white) is not used or may be for test input depending on the specific variant; Pin 3 (blue) connects to 0V DC common; Pin 4 (black) is the PNP switched output. The output is active high, meaning that when an object is detected within the sensing range, the output switches to +24V DC relative to common. The maximum load current is 200 mA, sufficient for direct connection to PLC inputs, small relays, or indicator lamps. For inductive loads such as relay coils, a flyback diode should be connected across the load to protect the sensor output from voltage spikes. The sensor includes short-circuit protection and reverse polarity protection on the power supply, preventing damage from common wiring errors.

Compatibility and Standards

The SLVA-4Kplus-2528 complies with relevant industrial standards including EN 60947-5-2 for photoelectric sensors. The sensor is CE marked, indicating conformity with European EMC and low-voltage directives. The sensor's robust EMC immunity ensures reliable operation in industrial environments with electrical noise from motors, drives, and welding equipment. The sensor is compatible with all major PLC brands' DC input modules, as the PNP output provides a standard 24V DC signal. For applications requiring NPN (sinking) outputs, alternative models in the 4Kplus series are available. The sensor's optical performance is consistent across the full operating temperature range, with minimal drift in sensing distance.

Maintenance and Troubleshooting

The SLVA-4Kplus-2528 requires minimal maintenance under normal operating conditions. The front lens should be cleaned periodically with a soft, lint-free cloth and mild glass cleaner to remove dust, oil, or other contaminants that could affect sensing performance. Do not use abrasive cleaners or solvents that may damage the lens coating. The sensor's IP67 rating means it can withstand washdown procedures, but high-pressure spray directly at the lens should be avoided. If the sensor fails to detect objects reliably, check the LED indicators: the green LED should be illuminated steadily when power is applied; the yellow LED should illuminate when an object is placed at the intended detection distance. If the yellow LED does not illuminate, adjust the potentiometer clockwise to increase sensitivity. If the yellow LED stays illuminated even with no object present, adjust the potentiometer counterclockwise to reduce the sensing range. If problems persist, inspect the M12 connector for corrosion or damage, and verify the power supply voltage is within specification.