Didactum Knowledge Base · Didactum Devices
Didactum PDU 4T
An overview of the device, its connections, and technical specifications of the Didactum PDU 4T – the switchable power strip with 4 C13 outputs, SNMP connectivity, built-in sensor ports, and an optional LTE modem for 19" technical, switching, and server cabinets.
What makes the PDU 4T stand out
Switchable power distribution with built-in sensor monitoring – for targeted protection and remote control of IT equipment.
4 switchable C13 outputs
Switchable individually or as a group manually, via SNMP, or sensor-triggered.
Up to 100 sensors
2 analog ports directly on the device, expandable via CAN bus to up to 32 devices.
Real-time alerting
Via email, SMS, SNMP trap, syslog, or a connected siren.
Web-based & SNMP
Compatible with Zabbix, PRTG, Nagios, and Check_MK, with no additional software required.
I/O control
Additional control of doors, fans, generators, UPS units, and circuit breakers.
Scalable
Up to 700 elements – notifications, triggers, timers, logic schemes.
LTE modem & SMS
Optional LTE modem for remote monitoring and switching on/off via SMS command.
Video surveillance
Optional USB camera plus display of up to 4 IP cameras in the web interface.
Made in EU
DIN-rail and wall mounting, with German support included.
Typical use cases
- Remote switching of server and IT equipment on and off
- Rebooting unresponsive PC, server, and storage systems
- Out-of-band management via remote SMS command (LTE modem required)
- Automatic shutdown of heat-sensitive systems in the event of overtemperature in the rack
- Immediate shutdown of loads when a UPS switches to battery operation
- Protection against water damage through immediate power cutoff on leak detection
- Physical environmental monitoring (temperature, humidity) in the rack
- Rack monitoring and integration with DCIM/NMS systems
Connections & controls
All ports, outputs, and LEDs on the front and rear of the PDU 4T, plus the complete connection and function diagram at a glance.
The PDU 4T separates the control/sensor side from the power side: the front houses the 19" rack mounting brackets, the 8 analog sensor inputs, LAN, USB, the modem slot, and all status LEDs (activity, error, alarm, CAN bus, output and relay status) as well as the built-in temperature sensor. The rear houses the 4 switchable C13 outputs, the power inlet (IEC C14) with fuse, the chassis ground, the battery expansion slot, the DC 12V backup supply, the factory reset button, the relay and dry-contact connections, the two CAN ports, the SD card slot, the Modbus RTU/OSDPv2 expansion slot, and the DIP switch for system recovery.
Front view
Front view: rack mounting brackets, analog sensors A1–A8, LAN, USB, modem slot, status LEDs, temperature sensor.
1U 19" rack mounting brackets
2× brackets for mounting the PDU in a 1U 19" rack slot.
Analog sensors A1–A2
2× RJ12 connectors for analog sensors with automatic detection (AutoSense).
LAN port
Ethernet 10/100 Base-T connection. Orange LED indicates network traffic, green LED the connection status (solid green = connected, blinking = connecting/system startup).
USB
Micro-USB port – for USB camera recording as well as USB flash drives for system logs and system recovery.
Modem slot
Slot for an optional LTE plug-in modem (available separately) for remote monitoring without a fixed IP network.
Label area
Space for a label, e.g. to identify the system with its IP address.
Restart button
Hold for 2 seconds and release to restart the system.
Status LEDs Activity / Error / Alarm
Activity (green) shows the system status (operation: 2 Hz blinking, successful update: 4 Hz blinking). Error (red) indicates errors and traffic – solid on for an error, 2 Hz blinking in update mode. Alarm is freely programmable via the web interface.
Temperature sensor
Built-in sensor with an accuracy of ±1°C.
CAN, output, and relay LEDs
CAN (green) shows the bus status (slow blinking: no connection, fast blinking: configuration in progress, solid: connected). R1–R4 show the switching state of the 4 C13 outputs, E1–E2 the status of the 12V/0.25A relay outputs (LED on = output active).
Rear view
Rear view: C13 outputs, power inlet, chassis ground, relay and dry-contact connections, CAN, SD card, expansion slot, DIP switch.
Outputs 1–4 (C13)
4× C13 outlets, 110–240V AC, 50/60Hz, switchable individually or as a group.
Power inlet
C14 inlet, 110–240V AC, 50/60Hz, with a 10A, 5×20mm fuse.
Chassis ground
M4 thread. Improves immunity to conducted and radiated RF interference.
Battery expansion slot
Slot for a rechargeable backup battery or a 9V backup battery (available separately). Only one expansion can be installed.
DC 12V Backup Power
Connection for the backup power supply.
Factory reset button
Hold for more than 5 seconds – the Error LED starts blinking, indicating the start of the factory reset. After 20–60 seconds the device is reset and reachable again once the Activity LED blinks.
Outputs 12V / 0.25A
Terminal outputs (electronic relay) for each output, with their own status LEDs (E1/E2) on the front panel.
Dry-contact inputs 1–2
Digital inputs (type IN), e.g. for reed contacts, fire alarm systems, or UPS units.
CAN 1 / CAN 0
Two digital RJ12 connectors for connecting CAN sensors, expansions, and devices on a CAN bus; cascadable.
SD card
MicroSD card slot with eject mechanism – for data storage or system recovery.
Expansion slot
Slot for either a Modbus/RTU or an OSDPv2 reader expansion (available separately). Only one of the two modules can be installed at a time.
DIP switch (N–R)
Normal mode: switch set to the left (should always be in this position). Recovery: switch set to the right, loads the clean system image from the SD card.
Connection and function diagram
Complete connection and function diagram of all ports, outputs, and expansion options of the PDU 4T at a glance.
What's included in the box
Please check the scope of delivery for completeness upon receipt and report any missing or damaged parts to your supplier immediately.
- Didactum PDU 4T1 pc.
- Power cable (IEC C14)1 pc.
- Terminal block, 2-pin, 3.81 mm (DC backup)1 pc.
- Terminal blocks for relay/contact connections1 pc. each
- DIN-rail mounting bracket1 pc.
- Quick start guide1 pc.
Dimensions in detail
Technical specifications
Device management
| Device management | Web, SNMP |
|---|---|
| Physical sensors | CAN, analog |
| Virtual sensors (e.g. Modbus TCP) | Yes |
Interface
| LAN | Ethernet 10/100 Mbit |
|---|---|
| Operating system | Linux |
| Interface | Any browser |
| Memory (RAM) | 128 MB |
| CPU speed | 720 MHz |
| Total CPU cores | 2 |
| Clock | Built-in clock |
| Timer | Built-in watchdog |
| USB | 1× USB 2.0 Type-C |
Sensors & logic
| Max. number of sensors | 100 (physical sensors, dry contacts, relays) |
|---|---|
| Max. number of elements | 700 (notifications, triggers, timers, logic, sensors, dry contacts, SNMP Get/Trap, etc.) |
| Temperature sensor | ±1°C board temperature, built-in |
Network / protocol support
| LTE gateway mode | Optional, via separately available LTE modem |
|---|---|
| Network protocols | DHCP, HTTP, HTTPS, SNMP (v1/v2c/v3), SMTP, FTP, syslog, TLS |
| Modbus TCP/IP | Yes |
| Modbus RTU (RS-485) | Optional, via expansion module |
| OSDPv2 reader expansion | Optional, via expansion module |
| VPN / SSL | Supported |
| DynDNS, static routing, RADIUS | Supported |
Notifications
| Alert types | Email, FTP log, syslog, SMTP, SNMP traps, SMS (modem available separately), web-to-SMS |
|---|---|
| Max. email recipients | 20 |
| Max. SMS recipients | 20 |
| Ping function | Built-in server ping function |
Power supply
| Power inlet | IEC C14, 110–240V AC, 50/60Hz |
|---|---|
| Outputs / outlets | 4× C13, switchable |
| Fuse | 10A |
| Power metering at outputs | No |
| Backup power input terminal | DC 12V emergency power supply, 3.81 mm, 2-pin |
| Min. power consumption | 1 W |
| Max. power consumption | 6 W |
I/O
| Analog port | 2 built-in ports, expandable via expansion module |
|---|---|
| CAN port | 1 port, up to 32 devices |
| Dry-contact inputs | 2 |
| Max. dry-contact outputs | 5 (normally-open contacts / digital outputs) |
| Relay outputs (12V / 0.25A) | 2 |
Video support
| USB cameras | 1 |
|---|---|
| IP cameras | up to 4 (display only) |
Storage & logs
| MicroSD slot | Up to 512GB (SDXC), FAT32 formatting possible |
|---|---|
| USB export | Logs, sensor data, settings |
| Log transmission | Syslog, FTP, email |
| Max. number of log entries | 10,000 logs/day ≙ 27 years |
Mechanics & housing
| Mounting | DIN rail, wall |
|---|---|
| Housing material | Plastic |
| Dimensions (L × W × H) | 440 × 44 × 80 mm |
| Weight | approx. 1.85 kg |
| External chassis ground | Yes |
Web interface panels
| Dashboard panel | Yes |
|---|---|
| Overall statistics panel | Yes |
| System tree panel | Yes |
| Dry-contact outputs/inputs panel | Yes |
| Camera panel | Yes |
Frequently asked questions
What is the Didactum PDU 4T and what is it used for?
The Didactum PDU 4T is an SNMPv1-, SNMPv2c-, and SNMPv3-compatible, IP-based power strip with 4 switchable C13 outputs for 19" technical, switching, network, and server cabinets. It is used for remote switching and rebooting of server and IT equipment, as an I/O controller for doors, fans, generators, and UPS units, and for physical environmental monitoring in the rack.
How many outputs does the PDU 4T have and how are they switched?
The PDU offers 4 switchable C13 outputs, which can be switched individually or as a group manually via the web interface, via an SNMP command, or automatically through connected sensors (e.g. in the event of overtemperature or when a UPS switches to battery operation).
Which sensors can be connected to the PDU 4T?
The PDU 4T has 2 analog sensor ports directly on the device and can be expanded via the CAN bus with up to 32 additional devices – including temperature, humidity, smoke, door, and water sensors. In total, up to 100 physical sensors, contacts, and relays can be managed simultaneously.
How are alarms and notifications sent?
The PDU 4T offers email notifications to up to 20 recipients, SMS delivery (optional via LTE modem) to up to 20 recipients, SNMP traps for network management systems, and syslog and FTP transmission. Additionally, external sirens or beacon lights can be connected via the 12V relay outputs.
Can the PDU 4T be controlled remotely via SMS?
Yes. With the optional LTE modem, the connected C13 outputs can be switched on and off via SMS command even during a network or DSL outage. Every switching command is acknowledged by the PDU via SMS, so execution is reliably confirmed.
What do the modem and expansion slots do?
The modem slot accommodates an optional, separately available LTE modem, enabling remote monitoring and remote SMS commands without a fixed IP network. The expansion slot accommodates either a Modbus/RTU or an OSDPv2 reader expansion – only one of the two modules can be installed at a time.
Can the PDU 4T be integrated into existing monitoring systems?
Yes. The PDU 4T supports SNMP v1/v2c/v3 as well as Modbus TCP/IP and, via expansion modules, Modbus RTU and OSDPv2. It can be integrated into common platforms such as Nagios XI, check_MK, Naemon, PRTG, Shinken, or Zabbix; Nagios plugins and MIB files are included in the scope of delivery.
Questions about the PDU 4T?
Our support team in Germany offers free advice on selection, setup, and sensors.
Scope of delivery
- 1 x Didactum PDU 4T monitoring device
- 1 x EU Schuko C13 0. 75 мм2 230V 10A cable
- 1 x UTP cable 3m
- 1 x Micro USB-C OTG adapter cable
- 1 x connector plug 3-pin, 3.81 mm
- 1 x connector plug 3-pin, 3.5 mm
- 2 x 19" rack brackets
- 6 x M3 x 8mm Phillips flat head screws
- 4 x self-adhesive rubber feet
- 1 x quick start guide
Manufacturer information:
Didactum® Security GmbH
Im Mühlenfeld 4
48163 Münster
Germany
Phone: (+49) 2501 92 90 160
Email: info@didactum-security.de
Extension modules
Extension units
Suitable sensors
CAN sensors
Warranty extension
Software
