We have installed the IP based Environmental Monitoring System 100 III in our server room. Now we bought the CAN box for connecting additional intelligent IP-sensors. Unfortunately, the CAN box is not recognized by the main sensor unit. Where is the problem?


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.


What cable should I use if I want to settle the Didactum sensors further away?


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.


What cable do I need for wiring the sensors Didactum® CAN and CAN-Units?


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.


Can Didactum be connected sensors / cascaded in series?


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.


I see on the Didactum CAN sensors and CAN units called. Terminators. Do I need to terminate the CAN devices?


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.


I use the combined PIR, Vibration and Temperature Sensor in our server room. The integrated vibration sensor reacts to every little wiggle in the server room and my  SNMP-enabled Didactum monitoring system sends me to a lot of e-mail alerts. What settings are useful for the integrated vibration detector?


The individual settings of this combined CAN sensor can be defined in web interface of your Network based Didactum monitoring device. The built-in vibration detector is set in your Didactum monitoring device too sensitively.


We use the 500 II monitoring device to measure important environment factors in our pharmaceutical warehouse. For connecting additional temperature & humidity sensors, we have procured the CAN expansion unit for sensors. Despite multiple attempts, this CAN box does not appear in the menu item "CAN Configuration". What are we doing wrong here?


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.



I see LEDs at the connector of my CAN expansion unit. What information is signaled here?


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.