Modular automation controller and edge gateway

UniPi Axon is a product line of programmable logic controllers (PLC) designed for industrial automation, production data collection, smart homes and other industrial and commercial IoT applications. The Axon line offers an extended operating temperature range, new computing module, 8GB eMMC onboard memory and a variety of specialized models (LTE, IQRF, 2× Ethernet, DALI).

Axon is suitable for a wide range of applications:

  • Industrial automation equipment
  • Production data collection
  • Smart home automation
  • Electrical installations
  • Energy management
  • HVAC control, BMS (Building Management System)
  • Remote control and SCADA
  • Construction sites
  • Garden and agriculture automation
  • Datacenters

…and many more!

Model overview

Name DI DO RO AI AO RS485 RS232 1-Wire
S105 4 4 - 1 1 2 1 1
S115 4 4 - 1 1 4 - 1
S155 (1) 4 4 - 1 1 2 1 1
S175 (3) 4 4 - 1 1 2 1 1
S205 8 - 8 - - 1 - 1
S215 8 - 8 - - 1 1 -
S505 - - - 4 4 1 - 1
S515 - - - 4 4 1 1 -
S605 (4) - - - - - 1 1 -
M205 20 4 14 1 1 2 1 1
M265 (2) 20 4 14 1 1 2 - 1
M525 8 4 5 5 5 3 1 1
M535 4 - 5 8 8 2 1 -
M565 (2) 8 4 5 5 5 3 - 1
L205 36 4 28 1 1 2 1 1
L525 24 4 19 5 5 3 1 1

(1) 2 x Ethernet (1 Gbit + 10/100 Mbit)

(2) wireless LTE module

(3) wireless IQRF module

(4) IEC 62386 (DALI-compatible)


The Axon product line is offered in three sizes and six model lines. The most numerous type is the Axon S (module size on DIN-rail: 7cm), allowing a wide range of possible applications while retaining compact dimensions.

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 Axon 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.

The construction of Axon is highly modular, allowing to create new I/O combination just by swapping I/O boards. Due to this feature, we could create for example the S205 and S215 models featuring 8 digital inputs and 8 relay outputs, or models with 4× RS485 or 2× Ethernet. Thanks to such modularity, we can also design and develop new solutions according to specific customer needs.

All Axon models are powered by the quad-core 1.2 GHz Allwinner H5 ARM processor featuring 1 GB RAM and internal 8GB eMMC memory. For quick communication, all units are equipped with 1Gbit Ethernet, Wi-Fi and Bluetooth. Alternatively, it is possible to add other custom wireless technologies according to the customer's needs. By default, all Axons feature a pair of USB 2.0 ports.

Inputs & Outputs

Depending on the particular model, the Axon controllers can be equipped with the following types of I/Os or their various combinations.

Digital inputs (DI) are designed for reading logic states represented by direct voltage levels. That makes DI's suitable for reading data from various two-state (binary) devices and sensors such as switches (on/off), motion sensors (movement/no movement), liquid level sensors (tank empty/tank full) etc.

Digital outputs (DO) are suited for switching various two-state devices such as lighting, door locks, shutter drives etc. DO's also feature power-width modulation (PWM) functionality that allows them to be used for analog control.

Relay outputs (RO) serve for switching device with a high current draw, ie. light bulbs, thermoelectric drives, water heaters, pumps, larger external relays etc.

Analog inputs (AI) are designed to measure voltage, current or resistance to read values from various analogue sensors such as thermometers, pressure meters, tensometers etc.

Analog outputs (AO) serve for control of multi-state external devices through direct voltage or current and are suitable for control and regulation of devices such as three-way valves, heat exchangers, electric motors etc.

Communication interfaces

By default all Axon PLCs feature one or more RS485 serial interfaces. Usually, the RS485 uses the Modbus RTU protocol and can be used to communicate with a wide range of devices such as Extension xS modules, energy meters, touchscreen HMI panels, PLCs from other vendors etc. A high number of devices can be connected to a single bus while the bus length can reach up to several hundred meters.

Selected models also feature a single RS232 serial line. In the field of automation, this interface is usually used for communication with various converters, closed-in technologies or display devices such as HMI panels.

A single 1-Wire bus is also included. This interface uses 2-3 conductors for collecting data from various 1-Wire sensors such as thermometers, humidity meters, light intensity sensors etc.). A single 1-Wire bus supports up to 15 devices, the overall length of the bus can reach up to 200 meters.

By default, all Axon controllers feature a single 1Gbit Ethernet port for network communication. The Axon S155 model is also equipped with an additional 10/100Mbit Ethernet.

Special features

IQRF functionality: the Axon S175 controller features a TR-76D transceiver for communication via the IQRF wireless network.

LTE functionality: the Axon M265 and M565 controllers feature an LTE module and a microSIM card slot to connect to the LTE wireless network.  


The Axon software was designed to be as open as possible. Customers are thus not limited to a single software solution and can choose from a variety of native, commercial or open-source platforms for control, communication and PLC configuration.

The basic software provided is the Linux OS along with the Modbus communication interface using TCP protocol - both are available free of charge. This basic solution is designed for simple user application implementation and supports remote access along with running the software on the unit itself. Combination of both methods provides the customer with the advantages of a distributed system.

The main supported solution is the Mervis control system - a platform developed under the IEC 61131-3 standard for PLC programming, that includes SCADA interface for remote management and monitoring, a comprehensible development environment, a human-machine interface (HMI) editor and an online/on-premise database for storing historical data and retrospective analysis of the controlled technology operation. A lifetime license code is included in the package of each Neuron controller for using the Mervis DB cloud database and the Mervis Proxy service.

The EVOK is an open-source application programming interface (API), designed primarily for remote access to our PLC units. It is a simple-to-use software allowing easy hardware access without the need for complex programming. EVOK is using six unified methods (or protocols), thanks to which the user does not have to write his/her code. That means any programming language can be used. These methods are: REST Web Forms, Bulk JSON, REST JSON, SOAP, JSON-RPC, WebSocket.

Recommended commercial software: the largest commercial SW platform is the IEC 61131-3 compliant CODESYS, designed to be used in modern industrial automatization projects.

Recommended open-source software: Node-RED with its web interface used for easy connection of hardware, API and online services through a comprehensive graphics editor allowing easy placement of code segments with a single click.