Industrial Raspberry Pi as automation controller and edge gateway

UniPi Neuron is a product line of programmable logic controllers (PLC) based on the Raspberry Pi computing platform, designed for industrial automation, production data collection, smart homes and other industrial and commercial IoT 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. 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.

Neuron 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

S103 4 4 - 1 1 1
S103-G* 4 4 - 1 1 1
S103-IQRF** 4 4 - 1 1 1
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
L203 36 4 28 1 1 1
L303 64 4 - 1 1 1
L403 4 4 56 1 1 1
L523 24 4 19 5 5 2
L533 12 4 10 9 9 3

* GSM/GPRS module

** IQRF compatible


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 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 Neuron can contain 1 (S-series), 2 (M-series) or 3 (L-series) I/O groups. Each group 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 group and monitors the communication with the CPU. All groups are labelled right-to-left from the main group (1).

Each I/O group processor is connected to the CPU and 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.

Computing module

Neuron controllers are powered by an integrated Raspberry Pi 3 Model B mini-computer featuring 1.2GHz quad-core CPU and 1 GB RAM and providing high computing power. That gives them more than enough performance for various performance-demanding applications. MicroSD memory cards are used as memory storage.

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.

Digital outputs (DO) are suited for switching various two-state devices such as lighting, door locks, shutter drives etc. DO's also feature pulse 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 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.

All Neuron models feature a single 10/100Mbit Ethernet port for network communication.

Special features

GSM/GPRS functionality: the S103-G model features a wireless GSM/GPRS module that allows the controller to use the GSM/GPRS network for sending alerts and notifications through the SMS service.

IQRF interface: the S103-IQRF features the TR-76D smart transceiver for communication using the IQRF wireless standard.


The Neuron 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.

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.