Please check the cable connection between your individual CAN devices and / or CAN sensors. Also check that the individual plugs are seated correctly. For test purposes, be sure to use the original CAN cables from manufacturer Didactum. A CAN patch cable is included in the scope of delivery of each CAN multi sensor and CAN unit. It has often been found that the RJ12 patch cable crimped by the customer is faulty or too short. Furthermore, please check for all CAN devices and / or CAN multi-sensors in the CAN bus line whether there is an error in the termination. The termination (TR switch) was often accidentally switched on (so-called TR ON position) in an intermediate device of the CAN Bus. Only the last CAN device in the CAN bus line has to be terminated! Please also check whether the "CR switch" on one of the CAN devices may be set to "ON" position. This must always be set to "OFF" for all CAN units and CAN sensors.

The digital CAN multi-sensors and CAN units from Didactum have LEDs which can signal the following states (status 09/2019):

  1. continuous red LED light, green LED is flickering: there is no communication with Didactum main control & monitoring unit. Please check the RJ12 wiring. Test the connection with the original patch cable (shielded).
  2. red steady light, green LED is not lit: there is a established connection to the Didactum main control & monitoring device, but the digital CAN sensor or CAN unit has not yet been configured in the WebGUI.
  3. red steady light is off, green LED is on constantly: the CAN sensors and CAN units are working properly with the Didactum main monitor.
  4. The LEDs are not lit: The CAN Sensor or CAN Unit is not powered correctly. Check the power supply of the main control unit and the RJ12 wiring. Please use the original CAN cable from Didactum. Please also check the correct termination of the sensor or the CAN unit. Under certain circumstances there may also be a technical defect.

Please check that your CAN unit has been correctly connected to your networked monitoring unit. Please also check the RJ12 CAN cable and the termination of CAN unit.

The installation instructions of the sensor expansion box can be found here. Furthermore, please check that the setting "Enable CAN" is activated in the web frontend under  Preferences" => "Network". Otherwise, no CAN sensors or CAN expansion units will be detected by your IP-based 500 II environmental monitoring unit.

You will find at all Didactum rack monitoring systems and sensors to the CAN and CAN expansion characteristics of the manufacturer Didactum called. Terminators in the form of a jumper.

Please always terminate the ends of each CAN line to possible reflections / interference on the CAN bus to minimize.

Shorter CAN connections should be terminated at least at one side. The scheduling of the CAN bus line is done by simply setting jumpers within a few seconds.

The group of Didactum sensors is divided into CAN-bus sensors (Control Area Network) and analog sensors.

The Rack Monitoring Systems 500/500 DC / 600 support both CAN-Bus, as well as analog Didactum sensors.

The CAN-bus sensors can be wired in series with Didactum and connected in series so. Save for wiring the sensors time and money. The two CAN-Bus terminals of Didactum alarm servers support a max. Total length of 300 meters. Ideal for environmental monitoring of large (IT) infrastructures.

Two sensors from the group of Didactum analog sensors can also be cascaded / connected in series.

This is true (as 06/2014) for the Didactum smoke detectors and the Didactum vibration detector.

Thus, for example 10 smoke detection sensors are concatenated for occupancy only an analog sensor ports with each other.

Please note that your Didactum room monitoring system for chaining more of these analog sensors detects it only as one sensor.

Alternatively, you can connect to the 8 analog sensor ports on the main unit or the sensor expansion unit (Product No. 14029), the respective analog sensors individually. Here, then, each sensor is individually displayed in the web frontend and can then be configured individually.

For more information, refer to the data sheets of the respective Didactum sensors.

Each Didactum CAN sensor and each Didactum CAN-Unit is a 2 meter shielded cable with shielded connectors.

If you long cable for CAN and CAN sensors require units, so please use a shielded cable brand.

Ideally, this 6-wire cable for low and high temperature ranges should be suitable and be resistant to oil and most chemical compounds.

Please make sure that the associated RJ12 connector of your CAN are also shielded bus cable.

The delivery of each Didactum analog sensor, a 2 meter long connecting cable and mounting material is included (mounting tape / screws).

The sensors are connected alarm system via Plug `n`Play with the Didactum IT and automatically identified.

If you want to install the Didactum analog sensors further away from the Didactum controller, so you can use regular phone cable.

The Didactum infrastructure monitoring systems support both 4 (6P4C) and 6-core (6P6C) telephone cable. A mixed cabling is also possible.


Please note that the Didactum DC sensors are wired exclusively by 6-wire telephone cable 6P6C.

Please check if the CAN bus is activated in the web interface of your main sensor unit.

Just go to menu item "Preferences" => "Network" => "Encable CAN" and activate it.

Then please click on the top right on the Floppy disk symbol to permanently save the settings of your networked monitoring system.