CAN Combination Sensor for Smoke, Temperature & Humidity

Early fire detection in the CAN bus network

The Didactum CAN combination sensor for smoke, temperature, and humidity combines a highly sensitive photoelectric smoke detector with precise temperature and humidity measurement in one device. Thanks to its high smoke sensitivity, it detects even low smoke concentrations and is therefore suitable as an early warning system in critical environments such as data centers, server rooms, and production facilities.

Each measured parameter — smoke, temperature, and humidity — is displayed as a separate element in the Didactum web interface. This makes it possible to define individual threshold values and trigger events such as notifications, alarms, or automated system responses.

As a robust CAN bus sensor, it supports daisy chaining with other CAN devices. Depending on the system configuration, 10 to 32 CAN units can be connected in a single CAN bus chain, enabling high scalability.

Sensor structure at a glance

The sensor has five key elements that are relevant for installation, wiring, and status checks.

Installation as a ceiling detector

As a classic smoke detector, the sensor is mounted on the ceiling or in the server cabinet. The included metal bracket makes safe and standards-compliant installation easier.

• Orientation: The sensor head must always face downward. Only in this position is reliable smoke detection ensured.
• Ventilation: The sensor must be sufficiently ventilated — the ventilation slots must not be covered or obstructed.
• Mounting height: The maximum mounting height is 6 meters.
• Mounting: The sensor head is detached from the base, then the base is secured to the metal bracket using the supplied M4×10 screws. The bracket itself is fixed to the cabinet frame with 4.8×19 mm screws. The sensor head is then reattached and snapped into place.
• Before commissioning: The red protective cap on the sensor must be removed before operation.

Test the sensor and avoid false alarms

The smoke sensor can be tested easily and without an open flame.

To test it, a standard PRF alarm tester spray is sprayed directly onto the sensor. The sensor then switches to alarm mode and the red operating LED lights up. After a short time — depending on the amount sprayed — the sensor automatically returns to normal operation.

Set the TR switch correctly

The TR switch ensures the correct termination of the CAN bus chain and must be set differently depending on the sensor’s position within the chain.

• Last sensor in the chain: The TR switch on the last sensor in the CAN bus chain must always be set to "ON".
• All other sensors: All other sensors or devices in the chain — whether at the beginning or in the middle — must be set to "OFF".

After connecting the sensors to the CAN bus, the red configuration LED on the rear side initially lights up. You then start the CAN bus polling via the web interface under "CAN Configuration". Once the sensors have been detected, the blue configuration LED also lights up, and the white operating LED on the front starts flashing every second during normal operation.

Measurement accuracy and operating range

In addition to smoke detection, the sensor simultaneously measures temperature and humidity with its own specified accuracy.

The smoke sensor works on the photoelectric principle and reliably detects even low smoke concentrations. Power consumption is around 100–120 mW, and the maximum distance to the monitoring unit is 225 m.

Areas of use for the sensor

The Didactum CAN combination sensor for smoke, temperature, and humidity is suitable for many applications where fire detection and climate monitoring are both required.

• Data centers: Monitoring smoke and heat protects valuable hardware and reduces downtime caused by fire incidents
• Server rooms: Combining smoke, temperature, and humidity monitoring helps prevent outages and protects critical IT infrastructure
• Industrial facilities: Early detection of smoke emissions from machines or production processes minimizes safety risks
• Warehousing and logistics: Protect sensitive goods such as food, pharmaceuticals, or artwork through continuous environmental monitoring
• Building management: Integrate into existing building management systems (BMS) for centralized control of safety and room climate
• Educational facilities: Use in classrooms and common areas to improve fire protection with automatic alerting
• Energy facilities: Protect against overheating and moisture damage in power plants and substations for maximum operational safety
• Telecommunications sites: Protect remote radio stations from equipment damage caused by smoke, overheating, or humidity

Functions in the web interface

Connecting CAN sensors

Up to 32 CAN units can be connected in a CAN bus chain, making the Didactum system highly modular. Up to 10 smoke combination sensors of this type can be connected in series to a single CAN port on the main module — using a new RJ11 cable from a free input of the already connected sensor to the next sensor in the chain.

An additional CAN power supply (12V/1A) is only required if the number of CAN devices in the chain exceeds 12 units. The maximum distance to the monitoring unit is 225 m.

What is included in the package

Please check the package contents for completeness upon receipt and report any missing or damaged items to your supplier immediately. In the event of transport damage, please contact the responsible delivery service directly.

• CAN combination sensor for smoke, temperature, and humidity1 piece
• RJ11/RJ12 6P4C cable1 piece
• Metal mounting plate (bracket)1 piece
• M4 x 10 mm screwsincluded
• 4.8 x 19 mm screwsincluded

Why this sensor is the right choice

Frequently asked questions