Unipi Neuron

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Unipi Neuron is a product line of universal programmable logic controllers (PLC) designed for applications in smarthome, commercial buildings, light industry and other fields of automation. It represents a modular and highly flexible device, which can be also used as a gateway for other devices.      Neuron is a product line of PLC units build to be universal and used in both Smart Home and Business applications and automation systems.

Unipi Neuron is a product line of programmable logic controllers (PLC) designed for smart homes, commercial and industrial applications. Neuron controllers represent a modular and highly flexible solution giving its users an option to remotely manage connected systems or individual devices through a variety of inputs/outputs and communication interfaces. Neuron controllers can also serve as gateways for other devices. The Neuron is an open platform and can be combined with custom code, integrated into already existing solutions, or used in combination with any of the supported open-source platforms.  


Thanks to its modular architecture and compact design, the Neuron represents a highly flexible and affordable solution for quickly expanding the field of smart technology. Customers can also utilize the Neuron for smart energy management to achieve better energy efficiency and reduce expenses.

The Neuron is suitable for

  • smart home automation
  • construction companies
  • electrical installations
  • energy management
  • HVAC automation
  • remote control and SCADA (Supervisory Control And Data Acquisition)
  • companies providing BMS (Building management system) services
  • garden and agriculture automation
  • geeks and DIY enthusiasts
  • beverage industry
  • datacenters
  • industrial monitoring
  • small industry projects
  • and many more

The Neuron is designed to be suitable for nearly every automatization project. That makes it a suitable choice for a wide range of technologies.


Each Neuron model is divided into one to three input-output (I/O) sections depending on the model, each containing a group of input, output and/or communication modules. Each I/O circuit board is controlled by its STM32 processor, which controls inputs and outputs and communicates with the central processing unit (CPU). Processors are using our firmware containing not only basic I/O functions, but also additional functions and features.

The internal topology of Neuron controllers

The Neuron can contain 1 (S-series), 2 (M-series) or 3 (L-series) I/O sections. Each section is equipped with its processor, to which interfaces of one or more I/O modules are connected. This processor handles all events on I/O modules of said section and monitors the communication with the CPU. All sections are labelled right-to-left from the main section (1).

Each I/O section processor is connected to the CPU and a central communication channel for all section processors. There is no communication between I/O sections. Each processor can also function independently on the CPU, allowing users to retain basic control of I/O modules in the event of CPU malfunction or software issue.

                Section 3                         Section 2                         Section 3

The following picture shows inputs, outputs and section labelling on the Neuron L203.

Computing module

Standard Neuron models are using an integrated Raspberry Pi 3 Model B/B+ as a computing module. The S103 (Raspberry Pi 4) then features an integrated Raspberry Pi 4 Model B. The following table compares the technical parameters of both options: 

Comparison of available computing modules
Type Raspberry Pi 3 Model B+ Raspberry Pi 4 Model B
CPU quad-core 1.2 GHz quad-core 1.5 GHz
Operating memory 1 GB RAM 2 GB/4 GB/8 GB RAM
Ethernet  300 Mbps 1 Gbit
USB 4× USB 2.0 2× USB 2.0, 2× USB 3.0
Wireless communication Wi-Fi, Bluetooth 4.2 Wi-Fi, Bluetooth 5.0
Available on all standard models S103 (Raspberry Pi 4)


The exact type of Raspberry Pi used can be determined by checking the product's version on its manufacturer sticker: 

- version 2.x = Raspberry Pi 3 Model B
- version 3.x = Raspberry Pi 3 Model B+
- version 4.x = Raspberry Pi 4 Model B

Inputs & outputs

Depending on the particular model, the Neuron 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. All digital inputs also feature counter functionality by default.

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. 

Modularity and OEM

The modular design of Unipi controllers offers customers with a wide array of hardware customization options. Circuit boards used in Unipi controllers have a universal design and can be freely combined or swapped if a new combination of I/Os is desired. This means customers that did not find a suitable model among standard Neuron models have the option to order development of a prototype featuring a customized architecture (a new combination of I/Os, additional serial interfaces, computing module selection etc.) or additional functionality (DALI, EnOcean, M-Bus, LTE etc.). For more info about the OEM solutions, please visit this link.

Communication interfaces

By default, all Neuron 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.

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.

The S103-G variant also features the Quectel M66 GSM/GPRS module and a SIM card slot, which allows the controller to connect to the GSM/GPRS network for sending notifications and alerts via SMS messages. 

All Neuron models feature a single Ethernet port for network communication. 


We designed the Neuron software 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, regulation and PLC configuration.

The basic software provided is the Linux OS along with the Modbus communication interface using TCP protocol - both can be downloaded free from our website. 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.

Main software platforms

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. 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
  • SOAP
  • WebSocket

These protocols cover absolute most of existing devices and software, which makes the EVOK a highly flexible software acting as a layer between the device or software itself and the EVOK webpage containing the control interface. The resulting software is easy to use enough for absolute beginners to use it.

For Mervis and EVOK, we provide full technical support.

Commercial solutions

Aside from the officially supported solutions Neuron controllers are also compatible with a wide range of third-party software platforms, both commercial and open-source. Detailed info can be found in the Other software overview.

Overview of compatible third-party solutions
Name Developed by Unipi OS image Tech. support Full functionality
Node-RED No Yes Partial1 All Unipi PLCs
HomeAssistant No No No Not guaranteed2
CODESYS No No No Not guaranteed2
REXYGEN No No Third-party Unipi 1.1
FHEM No No No Not guaranteed2
Pimatic No No No Not guaranteed2
Domoticz No No No Not guaranteed2
OpenPLC No No No Unipi Neuron, Unipi 1.1 (Not guaranteed)
openHAB No No No Not guaranteed2
Nymea No No No Unipi Neuron, Unipi Axon
(through SysFS)
Homebridge No No No Unipi Neuron, Unipi 1.1
Others3 No No No Not guaranteed2


  1. Tech. support provided only for the preparation of Unipi hardware for Node-RED implementation
  2. Functionality may be limited only to certain product lines or models. We recommend consulting the corresponding tech support or community forum
  3. Open-source solutions not included in the list that may be compatible with Unipi controllers. 

If you have any software-related questions, feel free to get in touch at info@unipi.technology, or contact our technical support at support@unipi.technology.


Digital input and output modules of the Neuron feature a set of functions allowing the user to customize the unit's functionality.

Digital inputs contain Debounce, Counter and DirectSwitch functions.

Debounce automatically compensates for signal fluctuations through a control interval measured in milliseconds. The impulse is then evaluated as valid only if it lasts for a given control interval. By that, the Debounce can prevent multiple returns of a single impulse. A correct Debounce setting is vital for a proper digital input operation.

The Counter function counts impulses received by the digital input. Counter inputs on Neuron controllers can detect pulses up to 10 kHz frequency and only tens or hundreds of microseconds long. This makes them suitable for reading data from energy meters, water meters, gas meters and other pulse meters used within systems for monitoring and regulation, ventilation, heating and air conditioning. Another possible application is reading engine revolutions per minute. Counters are automatically reset when their maximum value (4 294 967 295) is exceeded.

Note: Counter inputs on Neuron controllers are reset also in case of power failure. 

Digital outputs also support the pulse-width modulation (PWM) for transmitting two-value analogue signals.

Other functions

The master watchdog feature monitors the communication between the CPU and a local processor. If no exchange occurs within a pre-set timeframe, the MasterWatchdog automatically resets the device and I/O modules back into default settings.

Save default settings option allows each processor to save its default configuration. This configuration is then loaded after every device reboot triggered either by a manual restart or by a power outage.

Restart function provides the user with an option to trigger a restart of any I/O section and its reset back to default settings.

All Neuron models are also equipped with four customizable LEDs. These are labelled as X1 - X4 and can be used as a custom status indication.

Quality assurance

During the whole development and assembly process, we strongly emphasise the quality and reliability of all of our products. All components are manufactured in the Czech Republic by proven manufacturers. Each circuit board is also marked with unique QR code, allowing us to backtrack any individual component in case of failures or reliability issues. On the final product, every component can be backtracked, included the info indicating which person was responsible for testing and calibration.

Each circuit board underwent multiple-stage testing before the final assembly:

  1. visual check
  2. firmware upload test
  3. functionality test, I/O calibration and testing
  4. multiple modules assembly
  5. final test

Developer support

Unipi.technology supports startups, small projects and starting developers. Because of that, we offer an option to create a custom OEM variant of the Neuron with the batch size starting on 20 units. The customer can not only design his/her case graphic design but can also order a custom I/O architecture according to his/her needs. For larger companies, we also offer custom development, starting at 200 MOQ (Minimum Order Quantity). You can find more info here.

Neuron product line overview

Type S, size on DIN rail: 4 modules = 7 cm
S103 4 4 - 1 1 1
S103 (Raspberry Pi 4)1 4 4 - 1 1 1
S103-G2 4 4 - 1 1 1
Type M, size on DIN rail: 8 modules = 14 cm
M103 12 4 8 1 1 1
M203 20 4 14 1 1 1
M303 34 4 - 1 1 1
M523 8 4 5 5 5 2
Type L, size on DIN rail: 12 modules = 21 cm
L203 36 4 28 1 1 1
L403 4 4 56 1 1 1
L523 24 4 19 5 5 2
L533 12 4 10 9 9 3

1) Powered by Raspberry Pi 4 Model B
2) GSM/GPRS module

More information