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| Categories | Presence Detector |
|---|---|
| Power Supply Mode: | KNX bus power supply (DC 24V) |
| Certification: | CE RoHS |
| Communication: | KNX bus system |
| Payment Terms: | T/T,Western Union |
| Packaging Details: | Carton |
| Controltype: | Manual and Remote |
| Delivery Time: | 7 Days |
| Color: | Light grey |
| Model Number: | 5WG1255-2DB21 |
| Channel Configuration: | 16 independent control channels |
| Place of Origin: | EU |
| Operating Temperature: | -10°C to 50°C |
| MOQ: | 5 |
| Company Info. |
| Maituo Intelligent Technology Co.，Ltd |
| Verified Supplier |
| View Contact Details |
| Product List |
The 5WG1255-2DB21 (UP 255D21) is a KNX brightness sensor with integrated constant light level controller, designed for ceiling installation. Unlike presence detectors, its primary function is precise illuminance measurement via reflected light from the working plane below, with a range of 0–2,000 lux.
It supports mixed-light measurement to distinguish between daylight and artificial light contributions. The built-in constant light controller manages up to 5 lighting groups (1 main + 4 additional), maintaining a configured lux setpoint by automatically dimming or brightening artificial lighting. An integrated IR receiver supports 6-pair remote control, and the sensor can also detect motion for supplementary occupancy functions.
| Product Name | UP 255D21 – KNX Brightness Sensor with Constant Light Controller |
|---|---|
| Protocol | KNX/EIB Twisted Pair (TP) |
| Supply Voltage | 21–30 V DC via KNX bus (SELV) |
| Measurement Method | Reflected-light measurement from illuminated working plane |
| Brightness Range | 0–2,000 lux (at ~30% surface reflectance) |
| Monitoring Area | 360° horizontal, ~40° vertical; ~2 m diameter measurement zone |
| Light Source Detection | Mixed-light measurement (daylight + artificial light) |
| Constant Light Control | 1 main lighting group + up to 4 additional groups |
| Control Mode | 2-point control, fully automatic or semi-automatic |
| Sub-group Calibration | Auto calibration for up to 4 sub-groups |
| Auto Disable | Constant light control auto-disables on manual dimming |
| PIR Detection | Integrated motion detection (supplementary) |
| Detection Channels | 3 independent output channels + 1 HVAC channel |
| IR Remote Control | Integrated receiver/decoder, 6 button pairs |
| IR Button Functions | Switch, dim, scene recall, value send, shade control |
| Mounting | Ceiling, 60 mm flush-mount box (min. 40 mm depth) |
| Functional Blocks | 3 (Motion, Presence, HVAC) |
| Bus Coupling | Integrated, bus terminal connection |
| Programming | ETS software + front programming button + IR remote |
| Protection Class | IP 20 |
| Certifications | CE, KNX certified |
| ETS Compatibility | ETS 4.x and above |
The UP 255D21 is designed for spaces where maintaining a consistent illuminance level on the working plane is critical, regardless of changing daylight conditions.
Primary applications include offices with large windows, atriums, skylit corridors, retail showrooms, museums, and art galleries — any environment where daylight harvesting must be combined with artificial lighting to maintain visual comfort.
The constant light controller automatically compensates for daylight variations, dimming artificial lights when sufficient natural light is available and increasing output when it is not. The mixed-light measurement ensures accurate distinction between daylight and electric light contributions for precise control.
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