Each Didactum monitoring system is equipped with two 12V outputs. Here you connect the sensor potential free contact. Then connect this sensor to the potential free input of your "PAW-SERVER-PKEA" control unit. Use two-wire signal cable for this purpose. In the German language web interface of the monitoring system you then have the following options:

  • Switching on and off manually via the WebGUI
  • Interaction with our intelligent sensors (e.g. temperature sensor, humidity sensor, water leakage sensor, smoke detector etc.)
  • Switching via SNMP command or via BMS or network management software (e.g. Nagios, Icinga2, Check-MK, PRTG, Zabbix etc.)
  • SMS remote commands via cell phone (GSM modem required)

Since the monitoring systems are equipped with potential-free input contacts, you can also permanently monitor the fault indicators of your air conditioning units if desired. The fault messages are forwarded in the form of syslog, e-mail, SMS* (*via GSM-/4G-LTE- modem) and in the form of SNNP traps. A dial-up function* is also supported. Audio-visual alerting is also available as an option.

Yes. Specify whether the normal state of the fault annunciator is open or closed. Then set the desired notifications, alarms and actuator functions (siren or relay switching).

Yes, all Didactum monitoring units support SNMP protocols v1, 2c and v3 (encrypted). Any input contact present on the unit can be queried via SNMP command over TCP/IP network. Interval polling, with support for SNMPwalk commands, is also supported by the SNMP monitoring hardware.

If you need to switch opto-decoupled contacts via TCP / IP or SNMP, you can use the infrastructure monitoring systems of the Didactum series

  • Monitoring System 600 (DC)
  • Monitoring System 700 (DC)

can be used. These systems provide outputs for opto-decoupled (dry) contacts. These can be

  • manually via the German web interface
  • rule-based on the basis of stored logics
  • in interaction with connected digital / analog sensors or MODBUS-RTU capable meters

can be switched. At the same time, the monitoring systems 600 / 700 (DC) can send messages and alarms in the form of e-mail, SMS, Syslog and SNMP traps.

Dry contacts are mainly used in automation and building technology. With the support of a potential-free contact, also called dry contact, operating states, fault messages and diagnostic messages are (remotely) transmitted. Equipment and systems equipped with potential-free fault indicators include, for example:

  • Frequency converters, DDC-GA
  • alarm systems, video surveillance systems
  • Light control, door control, pump control
  • Heating, ventilation and refrigeration systems
  • Air conditioning units / air conditioning systems  
  • Fire alarm systems / extinguishing systems / sprinkler systems
  • Safety switches / circuit breakers
  • Fault alarm systems
  • Switching relays, switch cabinets

No. As the term "floating" implies, no voltage or current may be applied to the input contacts of the Ethernet-based measuring and monitoring device. Only connect pushbuttons, relays or switches to these dry contacts.

Didactum Monitoring System 300 is specially designed for DIN rail. Alternatively, you can order the monitoring system 100 with a mounting plate for DIN rail. This mounting plate for DIN rail is simply screwed under the monitoring system 100.

Every IP based measurement and monitoring device from Didactum is delivered including the required Phoenix connectors for connecting the digital contacts / dry contacts.

Didactum engineers have deliberately chosen this type of labeling. The number stands for the number of the dry contact input (Open) and the ground symbol for the ground (Closed).

A dry contact works like a switch. A dry contact can signal 2 states: Open (Normally Open) or Closed (Normally Closed). Any Didactum Ethernet-based measurement and control system can monitor dry contacts 24/7. Fault messages from connected air conditioning systems, ventilation systems, CO2 extinguishing systems, emergency diesel generators, load break switches, etc., are forwarded by the control system via e-mail, SMS, SNMP trap, syslog. Actuator functions, such as relay switching, are also supported.

No. Didactum's Ethernet-based telecontrol systems monitor dry contacts without the presence of current or voltage. Please make absolutely sure that the signal contacts to be monitored are really potential-free / current-free.

Yes. A 19 inch rack mount kit is an integral part of the scope of delivery of the Dry Contact expansion unit.

The inputs for floating contacts / dry contacts located directly on the mainboard of the Didactum monitoring systems are monitored in a polling period of 100 ms. The fault indication contacts connected to the internal expansion module of the 500 II fault indication system are interrogated by the SPI in a time period of 2000 ms. The internal, IC2 controlled Dry Contact expansion boards of the Didactum 600 / 700 high-end telecontrol systems support a polling period of 500 ms.

You can mount a switching relay with potential free contact on one of the two 12V outputs of the TCP/IP based Didactum Monitoring System 100. Didactum customers have already successfully implemented this solution with the "Eltako R12-100" switching relay.

For the connection of dry contacts, please use a two-wire signal cable. Optionally, you can also use two wires of a RJ45 network patch cable. To do this, simply disconnect the CAT5/5e/6/7 patch cable. You then connect this two-wire cable to the alarm contacts of your air conditioning system and the dry contact of your Didactum monitoring system.

The hazard and alarm annunciators are equipped with 2 different connectors for Ethernet connection of dry contacts / digital contacts.

You can mount a switching relay with potential-free normally open contact on one of the two 12V outputs of the TCP/IP based Didactum Monitoring System 100. Didactum customers have already successfully implemented this solution with the "Eltako R12-100" switching relay.


For some time, the manufacturer Didactum has also been offering the field-proven sensor potential-free contact. This sensor is simply connected to one of the two 12VDC output contacts of the IP-based measurement and control system. In the web interface you can then conveniently define the desired actions (open / close) of the potential-free output switching contact.

The IP-based monitoring system 500 II from the manufacturer Didactum can monitor up to 128 dry contacts in real time. For this purpose, you simply connect extension units with 64 fault signal inputs each. The messages of the collected potential-free contacts are transmitted by this monitoring system by e-mail or by SMS (via GSM- / LTE- modem or Web to SMS server). In addition, the switching status (open / closed) of the potential-free fault indicators is displayed in the tactical overview (German web interface).

The fault messages can also be transmitted remotely via SNMP interface standard (Simple Network Management Protocol) to automation software and / or building management systems. An active check of the fault alarm contacts is also supported. All events / switching operations of the connected floating contacts are recorded - including date and time information - in the syslog database of the monitoring system. The syslog can be sent at intervals via FTP upload or e-mail and evaluated in the control center.