Leuze KRT21M-09.PL3/42-M12 50127841 Contrast Sensors
The Leuze KRT21M-09.PL3/42-M12 is a high-precision Contrast Sensor (Part No. 50127841) designed for accurate contrast recognition, rapid switching response, and stable detection performance. Manufactured by Leuze, this Contrast Sensors solution helps identify subtle differences in color and contrast, supporting reliable product tracking and positioning in high-speed industrial automation applications.

| Brand | Leuze |
| Product | Contrast Sensors |
| Model Number | KRT21M-09.PL3/42-M12 |
Leuze KRT21M-09.PL3/42-M12 50127841 Contrast Sensors - Technical Specifications
| Specification | Value |
|---|---|
| Operating principle | 9 mm ± 3 mm |
| Type of connection | Connector |
| Thread size | M12 |
| Material | Plastic |
| No. of pins | 4 -pin |
| Encoding | A-coded |
| Design | Cubic |
| Ambient temperature, operation | -10 ... 55 °C |
| Ambient temperature, storage | -20 ... 70 °C |
| Degree of protection | IP 67 |
| Operating range | 9 mm ± 3 mm |
| Beam path | Focused |
| Light source | LED, RGB |
| Transmitted-signal shape | Pulsed |
| Light spot size [at sensor distance] | 1.5 mm x 5 mm |
| Light spot orientation | Vertical |
| Type of light spot geometry | Rectangular |
| Light beam exit | On face |
| Supply voltage | 10 ... 30 V, DC |
| Residual ripple | 0 ... 15 %, From UB |
| Open-circuit current | 0 ... 25 mA |
| Number of digital switching outputs | 2 Piece(s) |
| Voltage type | DC |
| Switching current, max. | 100 mA |
| Switching voltage | high: ≥(UB-2V) low: ≤ 2 V |
| Switching element | Transistor, PNP |
| Switching principle | Switching signal on mark |
| Switching frequency | 15,000 Hz |
| Response time | 0.03 ms |
| Dimension (W x H x L) | 31 mm x 53 mm x 80.1 mm |
| Housing material | Plastic |
| Plastic housing | ABS |
| Housing color | Black |
| Type of display | LED |
| Operational controls | Teach button |
The Leuze KRT21M-09.PL3/42-M12 (Part No. 50127841) operates by emitting light onto a target surface and measuring the reflected signal. Differences in contrast between printed marks, labels, backgrounds, or packaging materials are detected and processed by the sensor, allowing machines to identify reference points with high accuracy during continuous production operations.
Manufacturers use the KRT21M-09.PL3/42-M12 in packaging lines, label inspection systems, printing equipment, converting machinery, and web-guiding applications. It helps detect registration marks, verify product positioning, and synchronize cutting, sealing, and printing processes where precise mark recognition is essential for maintaining production quality.
Built for demanding factory environments, the KRT21M-09.PL3/42-M12 provides dependable operation during high-speed production cycles. Its robust construction supports reliable sensing performance in areas exposed to vibration, dust, and frequent machine activity, helping reduce detection errors while maintaining consistent process control over extended operating periods.