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Multi-IO 8-Layer Stackable HAT for Raspberry Pi

SKU: SM-I-021

Regular price $80.00


  • Multi-IO 8-Layer Stackable HAT for Raspberry Pi
  • Uses only I2C port, works with all Raspberry Pi versions from Zero to 5
  • Wide range 10-30V power supply provides also 5V/3A to Raspberry Pi
  • Two opto-isolated or four common ground digital inputs
  • Two 3-wire RTD ports with 24 bit delta-sigma A/D converters
  • Two 0-10V analog inputs 200 sps
  • Two 4-20mA analog inputs 200 sps
  • Two 0-10V analog outputs
  • Two 4-20mA analog outputs
  • Two 5A/24V relays with normal-open contacts and status LEDs
  • Two communication ports: RS485/Modbus and RS232
  • H-Bridge PWM Motor Driver
  • Two servo control ports
  • Nine Status LEDs (six general purpose)
  • On-board push-button
  • Hardware watchdog
  • Real Time Clock with battery backup
  • Pluggable Connectors
  • Stand-alone operation (No Raspberry Pi) using RS485/MODBUS
  • On-board 5V/2.5A step-down power supply for Raspberry Pi
  • Eight layer stackable for IO expansion
  • Uses only I2C port, all GPIO pins available
  • Works with any Raspberry Pi from ZERO to 5
  • ECCN Code EAR99
  • Command Line Driver
  • Python Library
  • Node-Red nodes


The Raspberry Pi IO Multi-IO HAT combines two of each of the most needed interfaces used in Industrial Automation: digital and analog inputs and outputs, RTD measurement and relays. Expandable to eight layers, it can perform from the simplest to the most complex Industrial and Home Automation tasks. 

ERRATA: The serial ports marking on the silkscreen is reversed. The lower port is RS485. The upper port is RS232.


24V POWER SUPPLY: Use standard industrial 24V power supply to power the board, or any DC power supply from 10V to 30V. Power requirement is 1A at 24V (24W). The Raspberry Pi IO Multi-IO HAT provides 5V and up to 3A to Raspberry Pi and any other HATs you might install on  the same stack.

DIGITAL INPUTS: Opto-isolated digital inputs can be jumper-selected in two different configurations: four inputs with a common ground or two fully isolated inputs.

RTD INPUTS: RTDs (Resistance Temperature Detectors) are resistive elements that change resistance over temperature. RTDs are capable of making measurements with accuracies of well under 0.1°C. Using 3 wires the voltage drop across the wires is also compensated. The Multi-IO HAT has two 3-wire RTD inputs which can read temperatures using PT100 sensors.

0-10V and 4-20mA ANALOG INPUTS: Two analog inputs can read 0-10V; Two more analog inputs can read 4-20mA signals. The inputs are processed using 12 bit A/D converters. Factory precision is approximately 1%. Precision up to 0.1% can be obtained through field calibration using command line functions.

0-10V and 4-20mA ANALOG OUTPUTS: Two analog outputs can drive 0-10V signals for light dimmers or industrial actuators. Two more analog outputs can drive 4-20mA current loops. The outputs are generated using 16 bit PWM timers. Discrete components limit the factory to 1% accuracy, but precision up to 0.1% can be obtained through calibration. Command line functions are provided for analog field calibration.

RELAYS: The Raspberry Pi IO Multi-IO HAT contains two relays which can drive AC or DC loads up to 5A and 24V. The current and voltage limitations are imposed by the board geometry. Loads up to 240V can be driven if conformal coating is applied to the board. The relays are SPDT, but due to space limitations only the normal open contacts are brought to the connectors.

RS485 COM PORT: The RS485 port can be accessed either from the local processor or from the Raspberry Pi. If the port is controlled by the local processor, the lines to Raspberry Pi are disconnected with jumpers, releasing the pins for other functions. The RS485 is using pins 8 and 10 of the GPIO connector.

RS232 COM PORT: The RS232 can be accessed only from Raspberry Pi. It is using pins 32 and 33 of the GPIO connector. If the port is not in use, pin 33 (Rx) can be disconnected with a jumper and can be used for other functions.

STAND-ALONE OPERATION: If the RS485 is used with the local processor,  the Raspberry Pi IO Multi-IO HAT card can be used stand-alone (no Raspberry Pi needed) and all I/O's can be accessed using standard MODBUS commands.

STATUS LEDs: A power led is flashing indicating the local processor is active. Eight more LEDs can be configured in software to show the status of any input, output or relays. If assigned to digital I/O's the LEDs show when the signal is high or low. If assigned to analog I/O's the LEDs can be triggered on predefined signal levels.

REAL TIME CLOCK: Install a CR2032 battery in the socket provided, to use the Real Time Clock. The battery can power the clock for many months. A software command is available to read periodically the battery voltage to decide when the battery needs to be replaced.

HARDWARE WATCHDOG: If the hardware watchdog is activated, the Raspberry Pi has to access the processor at a preset interval to ensure it is still operational. If the Pi fails due to software lockup, the local processor performs a hardware reset by cycling the power.

MICRO-MOTOR DRIVER: A micro-motor can be proportionally driven using a 5VDC/100mA motor driver and two PWM outputs from the processor.

SERVO MOTORS: Servo motors have three wires: power, ground, and signal. Two servo ports are available, driven by PWM pins from the local processor. 

PUSH BUTTON: The push button can be used to add manual input to any system. The button can also be used by Node-RED or other Raspberry Pi programming in an arbitrary manner.

PLUGGABLE CONNECTORS: Pluggable connectors ease connecting the card to external devices.  All the connector plugs are included with the card. To maximize the perimeter space, two level connectors are used for the RTD ports and the serial communication ports.

EXPANDABILITY: The Raspberry Pi IO Multi-IO HAT can be used with any Raspberry Pi or in stand-alone mode, connected through MODBUS to any standard PLC. Up to eight Raspberry Pi IO Multi-IO HATs can be plugged on top of each Raspberry Pi. 

RASPBERRY PI GPIO CONNECTOR: The Raspberry Pi IO Multi-IO HAT uses only the I2C ports to communicate with the Raspberry Pi, leaving all the other GPIO pins available for the user. Multi-IO HAT GPIO Connector

Multi-IO HAT for Raspberry Pi Industrial Applications




You can write your own application using the Command Line or Python Library provided. No programming is required if you use the Node-Red nodes we supply. You can drag-and-drop the functional blocks to design your application. 

Node-RED is a programming tool for wiring together hardware devices, APIs and online services in new and interesting ways. It provides a browser-based editor that makes it easy to design flows using nodes from a large library covering a wide range of automation tasks. Native Node-RED nodes are provided to access all the Multi-IO HAT functions.


When you purchase the I/O Learning Kit you will receive the following items:
1. Multi-IO Card
Multi-IO HAT for Raspberry Pi Industrial Applications
2. Mounting hardware
  • Four M2.5x18mm male-female brass standoffs
  • Four M2.5x5mm brass screws
  • Four M2.5 brass nuts
Mounting Spacers for Multi-IO HAT
3. Eight jumpers
Eight Jumpers for Multi-IO HAT
4. Mating connector plugs
Connector Plugs for Multi-IO HAT


  1. Plug your Learning KIT card on top of your Raspberry Pi and power up the system.
  2. Enable I2C communication on Raspberry Pi using raspi-config.
  3. Install the card software from
  • ~$git clone
  • ~$ cd /home/pi/multiio-rpi
  • ~/multiio-rpi$ sudo make install
  • ~/multiio-rpi$ multiio -h
    The program will respond with a list of available commands.

Customer Reviews

Based on 2 reviews
Rick Soper
It just works!

I’m accustomed to using breakout boards to build a solution. Getting everything powered and mounted is always a time-consuming task. This board makes building the solution so much cleaner and more reliable. With all the features on one board, it reduces the number of wires that can become loose. And then there is the Node-Red integration. Wow! A complete solution. Keep up the GREAT work!!

Amazing set of features compacted in a small space

Impressive set of featues for a HAT. Two level stackable connectors bring even more I/Os without increasing the space. RS485, RS232 and RTC, perfect.

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