Unipi Axon is a product line of programmable logic controllers (PLC) designed for monitoring, regulation and control of HVAC systems, smart home applications and other automation tasks. The Axon line offers an extended operating temperature range, new computing module, 8 GB eMMC onboard memory and a variety of specialised models (LTE, 2× Ethernet).
Basic hardware characteristics
The Axon product line is offered in three sizes and six model lines. The most numerous type is the Axon S (4 DIN modules size), allowing a wide range of possible applications while retaining compact dimensions.
Axon S105, M525, and L525 controllers
Axon controllers feature up to three input-output (I/O) sections 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 sections. 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, be it hardware specifications or Product branding.
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.
Computing module
Axon controllers are powered by a quad-core, 1.2GHz Alwinner H5 CPU and feature 1 GB RAM for excellent performance. The 8GB onboard eMMC memory then offers better reliability compared to systems relying on microSD cards as memory storage.
Inputs & outputs
Depending on the model, the Axon controllers are equipped by the following inputs and outputs, or their various combinations:
Digital inputs (DI) are designed to read binary logic states represented by direct voltage levels. That makes them suitable for reading data from various binary sensors and devices such as switches (on/off), motion sensors (movement detected/not detected), liquid level sensors (full tank/empty tank), etc. All digital inputs also feature counter functionality by default.
Digital outputs (DI) are intended for switching various binary devices (lighting, smart door locks, drives of shutters and blinds, etc.) through direct voltage. DO's also feature a Pulse-Width Modulation (PWM) function allowing to use the output for analog control.
Relay outputs (RO) are primarily used for switching two-state devices with higher current draw such as lightbulbs, thermoelectric valve drives, water heaters, pumps etc.
Analog inputs (AI) are designed to measure voltage, current, or resistance to read values from various analog 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 is suitable for control and regulation of devices such as three-way valves, heat exchangers, electric motors, etc.
Communication interfaces
By default, all Axon controllers feature RS485 serial lines. This type of interface usually uses the Modbus RTU protocol and can be used for communication with various devices such as Extension xS extension modules, energy meters, touchscreen HMI displays, controllers from other vendors, various sensors, etc. A single bus can support dozens of devices while its 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 available on selected models. 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
LTE functionality
The Axon M265 and Axon M565 controllers feature an LTE module and a microSIM card slot to connect to the LTE wireless network.
| Chip model | u-blox TOBY-L2 |
| Download speed | up to 150 Mb/s |
| Upload speed | up to 50 Mb/s |
| LTE bandwidth | up to 6 bands |
| GSM/GPRS bandwidth | up to 4 bands |
| WCDMA/DC-HSPA+ bandwidth | up to 5 bands |
The module allows the controller to serve as a primary or secondary internet access point for remote management and data transmission through the internet, or for sending and receiving SMS messages. In the role of a primary connection the controller functions as a web access point in locations without a landline internet connection. The secondary connection then comes into play as a backup in case of a primary Ethernet connection failure in technologies reliant on a connection between the technology and a supervision center. In the case of Ethernet failure, the controller automatically switches to the LTE mode, bridging the connection.
A brief start-up guide for the LTE module can be found on this link. Possible applications of Axon LTE controllers are available in the Axon LTE case study.
Software options
Thanks to the software openness of Unipi controllers customers can choose from a broad range of software solutions and are not limited to a single platform Among supported solutions are both commercial and open-source systems. Visit the Other software overview for the list of other supported solutions.
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's operation.
Aside from commercial platforms you can also choose any from the list of supported open-source solutions, or use the EVOK API (Websocket, REST,...) Modbus TCP, SysFS, or other tools for implementing your logic in any programming language. Visit this link for the list of supported software solutions.
Other features
Components of Axon controllers are protected by a durable aluminum chassis with IP20 protection. Thanks to an extended operating temperature range, Axons are suitable for industrial applications. The controllers are designed for installation on a standard DIN rail (35 mm), a DIN rail holder is included in the package.
Axon line model overview
| Model | DI | DO | RO | AI | AO | RS485 | RS232 | 1-Wire |
| Type S, the size on DIN rail: 4 modules (7 cm) | ||||||||
| S105 | 4 | 4 | - | 1 | 1 | 2 | 1 | 1 |
| S115 | 4 | 4 | - | 1 | 1 | 4 | - | 1 |
| S1551 | 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 | - |
| Type M, the size on DIN rail: 8 modules (14 cm) | ||||||||
| M205 | 20 | 4 | 14 | 1 | 1 | 2 | 1 | 1 |
| M2652 | 20 | 4 | 14 | 1 | 1 | 2 | - | 1 |
| M525 | 8 | 4 | 5 | 5 | 5 | 3 | 1 | 1 |
| M535 | 4 | - | 5 | 8 | 8 | 2 | 1 | - |
| M5652 | 8 | 4 | 5 | 5 | 5 | 3 | - | 1 |
| Type L, the size on DIN rail: 12 modules (21 cm) | ||||||||
| L205 | 36 | 4 | 28 | 1 | 1 | 2 | 1 | 1 |
| L525 | 24 | 4 | 19 | 5 | 5 | 3 | 1 | 1 |
1- 2× Ethernet (1 Gbit + 10/100 Mbit)
2 - wireless LTE module
