The VXT/CM-20PA is a color mark photoelectric sensor manufactured by VoxinTech, designed for precise color mark detection in industrial automation environments. Built on the diffuse reflection principle and equipped with a composite Red/Blue/Green LED emitter, this sensor accurately identifies printed registration marks, color-coded labels, and contrast boundaries on fast-moving production lines.
Key Features of the VXT/CM-20PA
The VXT/CM-20PA stands out in its category thanks to a combination of performance-oriented features that address real-world industrial demands:
- Triple-Color RGB LED: The sensor uses a composite LED with three emission wavelengths — Red at 625 nm, Blue at 470 nm, and Green at 525 nm. This tri-color approach gives it significantly better color discrimination capability compared to single-color alternatives, allowing it to detect a broader range of mark and background combinations.
- Dual Switch Mode: The sensor supports both L.ON (light entry action) and D.ON (shading action) modes, which can be switched on-site. This means the sensor adapts to virtually any mark-to-background configuration without requiring a different hardware model.
- Ultra-Fast Response Time: In color mark mode, the sensor responds in just 0.5 ms — fast enough for high-speed packaging and printing lines running several hundred meters per minute. In standard color mode, the response time is 2 ms.
- 4-Digit Digital Display: A built-in digital tube display lets technicians monitor detection thresholds and sensitivity values in real time. This eliminates the need for external calibration tools and speeds up machine commissioning.
- IP67 Protection: The sensor is rated IP67 — fully dustproof and protected against temporary water immersion. This makes it suitable for food processing, beverage filling, and other washdown-compatible manufacturing environments.
- PNP Open-Collector Output: With a PNP sourcing output and a load current capacity of up to 50 mA, the VXT/CM-20PA interfaces directly with a wide range of industrial PLCs including Siemens, Mitsubishi, Delta, Allen-Bradley, and Omron.
- Built-In Circuit Protection: The sensor includes reverse polarity protection and short-circuit protection, reducing the risk of damage during installation or wiring errors.
The VXT/CM-20PA Color Mark Photoelectric Sensor is widely supplied across major industrial hubs in India, including Delhi NCR, Mumbai, Pune, Chennai, Bangalore, Hyderabad, Ahmedabad, Kolkata, and Coimbatore. We also serve growing industrial regions such as Jaipur, Surat, Lucknow, Indore, Vadodara, Noida, Gurugram, Faridabad, Rajkot, Nagpur, Bhopal, Chandigarh, Ludhiana, Bhubaneswar, Visakhapatnam, Trivandrum, Madurai, Nashik, Vapi, Hosur, Aurangabad, and Patna.
How the VXT/CM-20PA Works
The VXT/CM-20PA operates on the diffuse reflection detection principle. The sensor emits a composite beam of red, blue, and green light toward the target surface. When the reflected light intensity changes — caused by a color mark passing through the sensing spot — the internal comparator circuit triggers a change in the output signal.
Color Mark Mode vs. Color Mode
In color mark mode, the sensor is optimized specifically for binary mark detection — for example, detecting a black printed mark on white packaging film. The response time in this mode is 0.5 ms, making it one of the fastest in its class for mark registration tasks.
In color mode, the sensor performs broader color-difference detection, capable of distinguishing between two or more surface colors. The response time here is 2 ms, still more than adequate for most industrial conveyor applications.
L.ON and D.ON Switching
The output polarity is fully configurable in the field. L.ON mode activates the output when reflected light is detected — ideal when the registration mark is lighter than the surrounding background. D.ON mode activates the output when reflected light is reduced — used when the mark is darker than the background, such as a black mark on white film. This adaptability eliminates the need to stock multiple sensor variants for different mark types.
PNP Wiring (3-Core Cable)
The sensor connects via a 3-core, 2-meter cable. Brown wire connects to the positive supply (+V), blue wire to 0V (ground), and the black wire carries the PNP output signal. Always refer to the official connection diagram included in the VoxinTech datasheet before wiring.
Industrial Applications
The VXT/CM-20PA is used across a wide range of industries wherever accurate, high-speed color mark or registration detection is required.
Flexible Packaging Lines: The sensor detects printed registration marks on film, foil, or laminate to synchronize the position of cutting blades, sealing jaws, or printing heads. This ensures every pack is cut and sealed at exactly the right point.
Label Dispensing and Application: In automatic label applicators, the sensor identifies the gap or color mark between labels on a continuous liner, triggering the label to be dispensed at the correct moment.
Pharmaceutical Blister Packaging: The sensor verifies correct foil positioning by detecting alignment marks before sealing, preventing misaligned blisters from reaching patients.
Food and Beverage Packaging: Its IP67 rating makes it safe for use in food production environments where moisture, condensation, or periodic washdowns are routine.
Printing and Converting Machines: Print registration control uses the sensor to detect reference marks between print stations, ensuring consistent color registration across multi-color print runs.
Textile and Garment Manufacturing: The sensor detects color marks on fabric rolls for automatic cutting, splicing, and pattern alignment operations.
Electronics Assembly Lines: Color-coded trays, substrates, or component carriers are identified using the sensor to verify correct part placement or sequence on conveyor lines.
Frequently Asked Questions
What is the detection distance of the VXT/CM-20PA? The sensor detects marks at a nominal distance of 10 mm with a tolerance of ±3 mm, giving a working range of 7 to 13 mm from the sensor face to the target surface.
Can the VXT/CM-20PA detect black marks on white film? Yes. This is one of its most common applications. Set the sensor to D.ON mode so the output activates when the dark mark reduces reflected light below the threshold.
Is the VXT/CM-20PA compatible with NPN PLCs? The sensor outputs a PNP (sourcing) signal. Most modern PLCs support PNP inputs natively. If your control system requires NPN (sinking) input only, a signal converter or relay interface will be needed.
What does IP67 mean in practice? IP67 means the sensor is completely sealed against dust (IP6X) and can withstand temporary immersion in water up to 1 meter deep for up to 30 minutes (IPX7). It is safe for humid, wet, and washdown environments.
Can the VXT/CM-20PA handle high-speed conveyor lines? Yes. With a switching frequency of up to 6 kHz and a response time of 0.5 ms in color mark mode, the sensor reliably tracks marks on fast-moving packaging and printing lines.
The ULS-24B-360-M84 is Voxintech’s flagship ultrasonic clear label sensor — engineered to detect transparent, clear, opaque, plastic, metallic, and BOPP labels on any backing material. As a direct manufacturer and supplier in India, Voxintech offers this sensor as a technically compatible, cost-effective alternative to market-leading brands including Leuze, Datalogic, Sick, Telemecanique (Schneider), and Omron — at competitive pricing with full technical support and same-day enquiry response.