UniPi Axon

UniPi Axon is our latest PLC product line, designed to be used in monitoring, regulation, smart home, HVAC and many other applications. In its core, Axon is improved and redesigned variant of the Neuron product line. The development goal was to capitalize on Neuron's strengths and to further improve them. Axon thus retains a high degree of modularity and flexibility - two of our products' most significant advantages.

Axon controllers feature up to three input-output (I/O) groups depending on the model, each containing a group of inputs, outputs and/or communication interfaces. The Neuron can contain 1 (S-series), 2 (M-series) or 3 (L-series) I/O groups.

Each I/O circuit board is controlled by its own STM32 processor, which controls inputs and outputs and communicates with the central processing unit (CPU). Processors are using custom firmware containing not only basic I/O functions, but also additional functions and features.

On the Axon line, the Raspberry Pi 3 Model B computer was replaced by a more compact industrial computer powered by 1.2GHz Allwinner H-5 quad-core CPU. Aside from its more compact dimensions, the most distinct difference is the replacement of Raspberry Pi's microSD memory card with an 8GB onboard eMMC memory. That makes the Axon more reliable during frequent memory rewrites.

The new computer is also provided with enhanced 1Gbit Ethernet and two USB 2.0 ports.

Depending on the model, Axon product line can offer up to:

  • up to 36 digital inputs
  • up to 4 digital outputs
  • up to 28 relay outputs
  • up to 8 analog inputs
  • up to 8 analog outputs
  • up to 4 RS485 universal bus ports
  • 4x IEC 62386 standard channels for smart lightning control (DALI-compatible)
  • a pair of 1Gbit Ethernet ports
  • various combinations of the above-mentioned

Digital inputs (DI) are designed for reading logical states (true or false), which are represented by levels of DC voltage. That makes them suitable for reading two-state sensors such as switches (on/off), movement sensors (movement/no movement), water level sensors (water present, no water) etc. The software detects logical 1 (true) if the input voltage between given DIx.y and DIGND is between 5-30V. If the voltage is lower than 3.5V, the state is evaluated as 0 (false)

Digital outputs (DO) are used for controlling two-state devices such as lights, door locks, window blinds etc. Digital outputs on our controllers also feature the PWM (Pulse-width modulation) function, enabling a special type of analogue control. Outputs are of the NPN type (open collector) and are able to control devices with voltage up to 50V and up to 750mA load current.

Relay outputs are used for control or switching of devices with higher current loads. ROs are thus suitable for controlling light bulbs, thermoelectric valve drives, water heaters, pumps etc. Relay outputs on UniPi controllers are rated for 5A max. current at 230V AC/30V DC voltage.

Analogue inputs (AI) can be used for 0-10V DC voltage or 0-20mA current measuring, making them suitable for reading values from analogue sensors such as temperature sensors, pressure meters, tensometers etc. On some controllers, two types of AI are available; the first type can be used to measure current or voltage while the second type additionally supports resistance measuring

Analogue outputs (AO) features two modes - 0-10V DC voltage or 0-20mA direct current. AI serves for control of devices with analogue input, such as three-way valves, lighting dimmers etc.

Depending on the model, the Axon can feature up to 4 RS485 serial lines, an RS232 serial line, a single 1-Wire bus or various combinations of all mentioned interfaces

The RS485 most often utilizes the Modbus RTU protocol and can be used for communication with a wide variety of devices such as energy meters, touchscreen HMI panels, PLCs from other vendors or the Neuron xS extension modules. The bus can communicate with up to 32 devices with its total length being up to several hundred meters.

The RS232 serial line is most often used for communication with HMI displays, various gateways or closed technologies.

The 1-Wire bus then can communicate with up to 15 sensors with maximum total length of the bus up to 100 meters, using either a 2-wire or 3-wire connection method.

Each Axon also features a single 1Gbit Ethernet for network communication