8-Port Sensor Expansion Unit

Function and Purpose

The 8-Port Sensor Expansion Box is a highly flexible expansion unit specifically designed to significantly increase the capacity of Didactum monitoring systems.

It enables a considerable increase in the number of analog sensors that can be connected to each compatible Didactum monitoring unit. Each individual 8-Port Sensor Expansion Box provides eight additional analog sensor ports.

This results in much greater scalability - ideal for monitoring complex, extensive, or particularly sensitive environments such as data centers, server rooms, production halls, storage complexes, or critical infrastructures in the energy sector, healthcare, or telecommunications.

Thanks to intelligent daisy-chain technology via the CAN bus, multiple 8-Port Sensor Expansion Boxes as well as other CAN-enabled devices and sensors can be easily and space-efficiently connected in a chain.

This means:

No additional hubs, no complicated cabling - only a continuous, stable data and power path. The chaining is done via robust CAN bus connectors known for high reliability and low latency. This creates a modular, easily expandable monitoring network that can flexibly adapt to growing requirements.

A key advantage: All connected sensors are automatically detected and integrated into the system. As soon as a sensor or expansion unit is connected to the 8-Port Sensor Expansion Box, it is recognized within a few seconds.

The Didactum software immediately displays the new measurement points in the user interface - with name, type, readings, and status. No manual configuration is necessary. This saves time, reduces potential errors, and enables rapid commissioning, even in large installations with dozens of sensors.

Up to 10–32 CAN devices can be connected in a chain. CAN sensors or extensions can be connected on a single CAN bus line.

Up to 24 units of the 8-Port Sensor Expansion Box can be operated on one CAN bus line.

The CAN-12V-1A power supply is required to ensure the additional power supply on the CAN bus line.

Scalability in Detail

Up to 10–32 CAN devices in one chain: This upper limit depends on the total cable length, signal quality, and the power supply used. In practice, this means you can operate not only several 8-Port Sensor Expansion Boxes but also digital inputs, relay modules, temperature sensors, humidity sensors, smoke detectors, door sensors, or motion detectors within a single CAN bus segment.
Up to 24 units of the 8-Port Sensor Expansion Box per CAN bus line: This corresponds to 192 additional analog sensor ports on a single monitoring unit! This allows even large-scale installations such as multi-story buildings, production lines, or distributed IT infrastructures to be monitored with just one central Didactum system.

Power Supply and Stability

In larger configurations with multiple expansion units, the power demand increases. This is where the special CAN-12V-1A power supply comes into play. It is integrated directly into the CAN bus line and reliably supplies power to all downstream devices. Without this additional power supply, voltage would drop too much in long chains or with many connected devices, which could cause instability or failures. With the CAN-12V-1A, the power supply remains stable even at maximum load. It is recommended to use the power supply approximately every 8–12 units or when the line length exceeds 50 meters.

Typical Application Scenarios

Data Centers: Monitoring temperature, humidity, airflow, water leaks, and power status across hundreds of racks – all centrally via a Vutlan system.
Industry 4.0: Connecting vibration sensors, pressure transmitters, level sensors, and analog process values in manufacturing environments.
Building Management: Centralized monitoring of air conditioning, heating, ventilation systems, and safety detectors in office complexes or hospitals.
Critical Infrastructure: Early detection of overheating, humidity, or power failures in substations, power plants, or telecommunications nodes.

Device connections

1. LEDs: “RUN” – indicates the device’s connection status to the main module, “ERROR” – indicates that the device has lost connection to the main module.

ERROR lights up constantly, RUN blinks – the device has no connection to the monitoring unit.
ERROR lights up constantly, RUN is steadily lit – the expansion unit communicates with the monitoring unit but is not integrated into the monitoring system (not configured).
ERROR remains on, RUN lights up continuously – the expansion unit is actively integrated as part of the monitoring system.

2. “A1..A8” – 8 RJ12 inputs for analog sensors with automatic detection.

3. “TR” – If the 8-port sensor expansion box is the last unit in a CAN bus chain or is connected in a CAN bus chain longer than 10 meters, the terminator must be set to the “TR” position (switched to the left). Otherwise, “TR” should always be switched to the right.

4. “CAN1 CAN2” – two equivalent digital RJ12 ports for connection to the main module, CAN sensors, or CAN extensions in the CAN bus, with automatic detection.

5. “Power” – for connecting an external power supply of 12 V DC.

Connecting the sensors

Dimensions

Installation

Wall mounting

At the bottom of the housing, there are four M3 threaded holes. You can attach wall brackets to these holes and then use them for wall or surface mounting. The wall brackets must be ordered separately.

DIN rail mounting

At the bottom of the unit, there are two M4 threaded holes. Use these to attach the DIN rail bracket. This allows the device to be mounted on a DIN rail. The DIN rail bracket must be purchased separately.

Rackmount kit mounting

It is possible to use a rackmount kit to install one or two 8-port sensor expansion boxes in a 1U rack space. The rackmount kit must be purchased separately.

If you want to mount the 8-port sensor expansion box on the bracket, loosen two M3 screws for this purpose.

The parts of the rackmount kit are supplied unassembled.

Use M3 screws to attach the 8-port sensor expansion box to the rackmount kit.

Setup

Connect the CAN input of the unit to the CAN input of the previous CAN unit or the monitoring system using the supplied RJ11/RJ12 cable. The red LED will light up. Adjust the TR bus terminators on the connected CAN units accordingly.

CAN bus terminators TR (position 2 on the expansion box) should only be set to ON at the last CAN unit connection and must be set to OFF (1,2) on all intermediate units.

A CAN bus must not include more than eight CAN units, sensors, and/or other CAN devices.

Usually, an external 12 V 0.5 A power supply is connected to the socket labeled PWR (point 2 in the overall diagram).

However, if only one 8-port sensor expansion box is connected and the cable length from the monitoring unit to the 8-port sensor expansion box does not exceed 10 m, the expansion unit will operate without an external power supply. In all other cases, the use of an external power supply is recommended.