Neuron product line introduction

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The UniPi Neuron is a modular Programmable Logic Controller (PLC) product line, designed to be used as a central control unit for control, regulation and monitoring of smart building systems, HVAC (Heating, Ventilation, Air Conditioning) systems and industrial automation.


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.

Neuron is suitable for

  • smart home automation
  • construction companies/li>
  • electrical installations
  • energy management
  • HVAC automation
  • remote control and SCADA (Supervisory Control And Data Aquisition)
  • 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

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


Basic Neuron S103 model diagram

Each Neuron model is divided into one to three input-output (I/O) groups depending on the model, each containing a group of input, output and/or communication modules. 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 our own firmware containing not only basic I/O functions, but also additional functions and features.

Neuron product line internal topology

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

I/O modules of each group are labelled to minimize the risk of mismatch. We offer 12 models of Neuron PLC unit, which can be equipped with

  • up to 64 digital inputs
  • up to 4 digital outputs
  • up to 56 relay outputs
  • up to 9 analog inputs
  • up to 9 analog outputs
  • up to 3 RS485 universal bus ports
  • various combinations of the above-mentioned

As the CPU of all Neuron units, the Raspberry Pi single-board computer is used. Each I/O group processor is connected to the CPU and to a central communication channel for all group processors. There is no communication between I/O groups. 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.

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

                  Group 3                                     Group 2                                      Group 1


Thanks to their modular design, I/O boards are fully interchangeable, allowing the customer to either choose from default I/O module combinations or to create a custom architecture according to specific needs. Neuron thus can be customized to suit all customer needs without the need to develop a suitable hardware first.

Communication interface

As standard, all Neuron units are equipped with the RS485-Modbus and the 1-Wire communication interfaces. The 1-Wire low-speed is used for passive data collection from various attached sensors such as thermometers, humidity meters and other measuring devices. The 1-Wire low-speed data bus allows up to 15 devices with unique HW addresses to be connected to each channel. Modbus is then a communication protocol using the RS485 serial bus and serves as an interface for connecting and programming various devices sharing a given protocol. As standard, all Neuron units are equipped with one RS485 bus - the exception is the Neuron 500 line with up to 3 RS485 bus ports. These units then can be connected to devices using up to three communication protocols.

Inputs and outputs

Depending on the model, I/O groups can be equipped with digital, analogue and/or relay modules, or a combination of all types. Each type has its own specific features and usage.

Digital inputs are designed for a reading of binary values (0/1, on/off, open/closed etc.) and are thus suitable for connecting switches, motion sensors, window or door magnetic locks etc.

Digital outputs can be used to control binary state devices, such as lightning switches, window shutters control, remote door control etc.

Analogue inputs are used to receive either 0-10V voltage or 0-20mA current signals. Alternatively, they can be used for reading data from corresponding sensors, such as resistance thermometers. The user can adjust the input mode via corresponding control software.

Analogue outputs are used for control of external devices such as three-way valves or heat exchangers via 0-10V voltage or 0-20mA current signals. Analogue outputs allow current or voltage regulation - alternatively, Group 1 inputs can be used in combination with resistance thermal sensors.

Relay outputs are designed for switching two-state devices via alternating or direct voltage. Relays thus can be used to switch boilers, water heaters, electric motors or other stronger relays. Neuron unit relays are designed for 5A maximum current and 250V alternating/30V direct voltage.

Aside from Neuron PLC product line, we also offer a range of Unipi Extension extension modules. These modules are based on the basic Neuron S103 unit, but the Raspberry Pi CPU is replaced by additional I/O group based on the particular model. The XS-line thus represents a simple and cheap way of system extension by adding more inputs and outputs without the need to purchase more units. Extension modules are connected via RS485 universal bus and can be used in combination not only with Neuron, but also with any other PLC unit in cases when other manufacturers either don't provide their own native extensions, or their purchase would be too expensive.

Depending on the model chosen, extension modules can provide the user with:

  • up to 24 additional digital inputs
  • up to 14 relay outputs
  • up to 4 analogue inputs
  • up to 4 analogue outputs


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.

Native software platforms

Our main SW platforms are Mervis and EVOK.

Mervis platform is a collection of tools and applications for advanced control and regulation. Apart from the control software, development application and user-friendly graphic interface are also provided, along with SCADA interface for remote control and monitoring. The platform was developed in accordance with the IEC 66131-3 standard for PLC software. Mervis is license-based, with licenses being offered in our e-shop.

EVOK is designation of our 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 own 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. Resulting software is easy to use enough for absolute beginners to use it.

For Mervis and EVOK, we provide a full technical support.

Commercial software

The largest commercial SW platform is the IEC 61131-3 compliant CoDeSyS, designed to be used in modern industrial automatization projects.

The REX software can serve as an alternative, providing a set of tools and applications for automatization projects and allowing an easy PLC programming via a comprehensive graphic interface.

Graphics programming is also used by the Wyliodrin, platform, which allows the user to use a simple drag-and-drop scheme to quickly create control code for various basic functions, such as switching off lights, motion sensors control etc

HomeSeer HS3 platform then offers basic software for controlling devices such as lightning switches, thermostats, door locks and many more.

Commercial platform support is provided externally by platform's respective developer.

Open-source platforms

As we emphasize the openness of our system, our products can utilize a wide range of open-source platforms. Currently, we offer the following platforms:

  • Jeedom
  • FHEM
  • PiDome
  • Pimatic
  • Domoticz
  • DomotiGa
  • Node-RED

From above-mentioned, we can highlight the Node-RED with its web interface used for easy connection of hardware, API and online services through a comprehensive graphics editor allowing an easy placement of code segments with a single click.

The FHEM platform offers a broad support of various protocols and is particularly suited for combining wired and wireless systems. The DomotiGa platform then provides the user with development interface for developing smart home applications based on the Linux OS. Open-source platform support is provided externally by respective developers.


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.

Counter function counts impulses received by the digital input and resets itself when a pre-set peak value is reached. With this function, the digital input can be used for reading data collected by digital flow meters, thermometers and other digital measuring devices.

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 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 manual restart or by a power outage.

Restart function provides the user with an option to trigger a restart of any I/O group 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 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 a multiple-stage testing prior to 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 supports startups, small projects and starting out 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 own case graphic design but can also order a custom I/O architecture according to his/her needs. For larger companies, we also offer a custom development, starting at 200 MOQ (Minimum Order Quantity). You can find more info here.