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UniPi Neuron

UniPi Neuron is a modular programmable logic controller (PLC) product line designed for control, regulation and monitoring of smart building systems, HVAC (Heating, Ventilation, Air Conditioning) systems and both home and industrial automation systems. Thanks to its modular architecture and compact design, the Neuron represents a highly flexible and affordable solution for quickly expanding field of smart technology. Customers can also utilize the Neuron for smart energy management to achieve better energy efficiency and reduce expenses.

Each Neuron model is divided into one to three input-output (I/O) groups depending on model, each containing a group of input, output and/or communication modules. The Neuron 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.

All components are encased in a durable metal case made from eloxed aluminium with IP20 degree of protection against external hazards. The case can be customized - for more info, see the OEM solutions page

All Neuron models are using the Raspberry Pi 3 Model B as its central processing unit. Each I/O group 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.

UniPi Neuron internal topology

Depending on the model, Neuron product line can offer up to:

  • 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

Digital inputs use binary logic; that makes them two-state inputs utilizing DC voltage pulses. Axon digital inputs are designed for 5-40V DC voltage range, receiving voltage pulses from corresponding external devices. Typical examples of such devices are digital lightning switches, magnetic contacts in windows or doors, motion sensors etc. It is also possible to connect pulse meters (energy meters, water flow meters etc.).

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

Analog 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.

  • voltage measurement 0-10 V (16bit resolution)
  • voltage measurement 0-2.5 V (24bit resolution)
  • current measurement 0-20 mA (16bit resolution)
  • resistance measurement (from sensors PT100, PT1000, NTC) in three wire (three conductors, 0-100 Ω, 24bit resolution) or two wire (two conductors, 0-1960 Ω, 24bit resolution) wiring method..

Analog outputs operate in voltage range 0-10 V (12bit resolution). Analog inputs allow more precise measurement (they have higher bit resolution). Group 1 outputs allow the user to set required output voltage current, while Group 2 outputs can be used for resistance measurement.

Details about AI/AO additional functionality can be found in Neuron technical manual

Relay outputs are dimensioned for a maximum voltage of 250V AC/30V DC with maximum current of 5A. The main purpose of these relays is switching of two-state external devices through alternating or direct voltage. Typically, relay outputs are used to switch boilers, electric motors, waterheaters or other, stronger relays.

Along with basic I/O features this product offer additional unique features, either improving its performance or making it ready for cases of emergency.

Direct Switch

Direct switch allows you to set appropriate device reaction based on input signal without a need of master control unit (Raspberry Pi computer build inside Neuron controller). This function is great for real-time applications. It also comes in handy in case of malfunction of the master control unit.

Default configuration

It is possible to store default settings inside the module memory and when the device reboots, it configures itself according to stored default settings.

Master Watchdog

This function periodically controls communication with the master control unit (Raspberry Pi computer). If for a period predetermined by a user there is no communication with the master unit, it will load and set the stored default settings. Your applications will function even in emergency cases.

By standard, all Neuron models feature up to three RS485 serial lines for connecting of external devices or extension modules (i.e. 05-extensions). One line can communicate with up to 256 devices, using the Modbus RTU protocol.

Each Neuron also features a single 1-Wire bus for passive reading of data from corresponding 1-Wire sensors (humidity sensors, temperature sensors etc.). One bus can receive data from up to 15 sensors at once (provided a suitable 1-Wire hub is used).