Home » Multi-IO HAT 8-Layer Stackable for Raspberry Pi
Multi-IO HAT v2.0 industrial automation expansion board for Raspberry Pi with digital inputs, RTD ports, analog I/O, relays, servo control, and serial communication ports.
Multi-IO HAT 8-layer stackable expansion board for Raspberry Pi with relays, analog and digital inputs/outputs, RTD ports, RS485/RS232 communication, and power supply.
Multi-IO HAT 8-layer stackable expansion board with digital and analog I/O, relays, RTD inputs, and communication ports for Raspberry Pi.
Multi-IO HAT 8-layer stackable industrial automation expansion board for Raspberry Pi with relays, analog and digital I/O, RTD inputs, and communication ports.
Multi-IO HAT 8-layer stackable expansion board for Raspberry Pi with digital, analog inputs/outputs, relays, RTD ports, RS485/RS232 communication, and real-time clock.
Multi-IO HAT 8-layer stackable Raspberry Pi I2C interface with analog, digital inputs/outputs, relays, RTD ports, and communication ports for industrial automation.
Multi-IO Stackable HAT 360
Multi-IO HAT v2.0 industrial automation expansion board for Raspberry Pi with digital inputs, RTD ports, analog I/O, relays, servo control, and serial communication ports.
Multi-IO HAT 8-layer stackable expansion board for Raspberry Pi with relays, analog and digital inputs/outputs, RTD ports, RS485/RS232 communication, and power supply.
Multi-IO HAT 8-layer stackable expansion board with digital and analog I/O, relays, RTD inputs, and communication ports for Raspberry Pi.
Multi-IO HAT 8-layer stackable industrial automation expansion board for Raspberry Pi with relays, analog and digital I/O, RTD inputs, and communication ports.
Multi-IO HAT 8-layer stackable expansion board for Raspberry Pi with digital, analog inputs/outputs, relays, RTD ports, RS485/RS232 communication, and real-time clock.
Multi-IO HAT 8-layer stackable Raspberry Pi I2C interface with analog, digital inputs/outputs, relays, RTD ports, and communication ports for industrial automation.
Multi-IO Stackable HAT 360
SKU: SM-I-021

Multi-IO HAT 8-Layer Stackable for Raspberry Pi

Four digital Inputs, 2xRTD ports, 2x0-10V Inp and Out, 2x4-20mA In and Out, 2x5A/24V Relays, 2xServo ports, H-Bridge Motor, RS485, RS232, Watchdog.

In stock
$100.00

Overview

The Multi-IO HAT for Raspberry Pi combines digital inputs, RTD temperature measurement, voltage and current analog I/O, relays, motor control, and two communication ports in a compact, stackable board for industrial and home automation.

  • Digital, RTD, voltage and current analog I/O, and relays on one board
  • RS485/MODBUS and RS232 communication ports
  • H-Bridge motor driver and two servo control ports
  • Up to 8 cards of each type can be stacked and mixed with other Sequent HATs for virtually unlimited I/O expansion
  • Hardware watchdog, Real-Time Clock, and stand-alone MODBUS operation without Raspberry Pi

Works with Open Automation Software

Compatible with widely used tools for control, monitoring, and system integration.

Command Line Python CODESYS Home Assistant

INTERFACES AND I/O

I/O's Communication Software Integration
• Four Optically Isolated Digital Inputs (event counters up to 32 kHz) • I2C Port to Raspberry Pi • Command Line
• Two 3-Wire RTD Inputs (PT100) • RS485/MODBUS Port • Python Library
• Two 16-bit 0-10V Analog Inputs • RS232 Port • CODESYS Driver
• Two 16-bit 4-20mA Analog Inputs • Home Assistant
• Two 13-bit 0-10V Analog Outputs
• Two 13-bit 4-20mA Analog Outputs
• Two 5A/24V Relays (normally open contacts)
• H-Bridge PWM Motor Driver
• Two Servo Control Ports
Other Features
• Nine status LEDs (one power LED, six general purpose software-configurable LEDs)
• Wide range 10–30V power supply delivers 5V/3A to Raspberry Pi
• On-board push button for manual input
• Hardware watchdog and Real-Time Clock with CR2032 battery backup • Pluggable connectors; two-level connectors for RTD and serial ports
• Stand-alone MODBUS operation (no Raspberry Pi required) • Eight-level stackable; uses only I2C, all GPIO pins available

DESCRIPTION

The Multi-IO HAT provides everything needed to build versatile industrial and home automation systems with Raspberry Pi — combining sensing, signal conditioning, actuation, communication, and motor control on a single board.

Digital Inputs

Four optically isolated digital inputs can be jumper-selected between two configurations: four inputs with a common ground or two fully isolated inputs. Inputs can also function as event counters up to 32 kHz.

RTD Inputs

Two 3-wire PT100 RTD inputs with 24-bit delta-sigma A/D converters measure temperature with accuracy well under 0.1°C. The 3-wire connection compensates for voltage drop across long cable runs.

Analog Inputs

Two 16-bit 0-10V inputs read voltage signals; two 16-bit 4-20mA inputs read current-loop sensors. Factory accuracy is approximately 1%; field calibration using command-line functions achieves up to 0.1% precision.

Analog Outputs

Two 13-bit 0-10V outputs drive light dimmers and proportional actuators; two 13-bit 4-20mA outputs drive current-loop devices. Factory accuracy is approximately 1%; command-line calibration functions achieve up to 0.1% precision.

Relays

Two SPDT relays switch DC or AC loads up to 5A at 24V. Boards with conformal coating can drive loads up to 240V. Only the normally-open contacts are brought to the connectors to maximize perimeter space.

Real-Time Clock

The Real-Time Clock with CR2032 battery backup keeps accurate time through power failures, enabling data logging and time-stamped event recording. A command is available to read the battery voltage and determine when replacement is needed.

Hardware Watchdog

The hardware watchdog automatically power-cycles the Raspberry Pi if the software becomes unresponsive, ensuring continuous operation in unattended deployments. It activates after the first reset command is received from the Pi.

Status LEDs

A power LED flashes to indicate the local processor is active. Eight additional LEDs can be configured in software to display the state of any input, output, or relay — triggering on digital highs/lows or on programmable analog thresholds.

Motor Driver & Servo

An H-Bridge 5VDC/1A PWM motor driver enables proportional control of micro-motors. Two dedicated servo ports driven by PWM signals from the local processor allow independent servo motor control.

Push Button & Stacking

An on-board push button provides manual input to any application. Up to eight cards can be stacked on a single Raspberry Pi; the card uses only the I2C port, leaving all other GPIO pins available for other use.

TECHNICAL DETAILS

CARD LAYOUT

Multi-IO HAT board layout showing connector positions, DIP switch, and GPIO header for Raspberry Pi

MECHANICAL SPECIFICATIONS

Multi-IO HAT Mechanical Specifications

DIP SWITCH AND STACKING

The onboard six-position DIP switch configures both the stack address and the RS485 port behavior. Cards of different Sequent HAT types can be freely mixed in the same stack.

Switch Name Function
ID0 Stack ID bit 0 Binary stack address bit 0 (LSB) — sets card level 0–7
ID1 Stack ID bit 1 Binary stack address bit 1
ID2 Stack ID bit 2 Binary stack address bit 2 (MSB)
RX RS485 RX select ON: Raspberry Pi receives RS485 directly
TX RS485 TX select ON: Raspberry Pi drives RS485 directly
TERM RS485 termination Enable on the last card in an RS485 chain to prevent signal reflections

POWER REQUIREMENTS

Power supply: The card requires an external 10–30VDC power supply connected to its own pluggable power connector. Power requirement is 1A at 24V. The card supplies 5V and up to 3A to the Raspberry Pi over the GPIO bus, eliminating the need for a separate Raspberry Pi power supply.

PLUGGABLE CONNECTORS

All I/Os connect to pluggable screw terminal connectors. Two-level connectors are used for the RTD ports and serial communication ports to maximize the available perimeter space. All mating connector plugs are included with the card.

FIELD CALIBRATION

All analog inputs and outputs are factory-calibrated.
However, firmware commands allow the user to recalibrate the board or perform higher-precision calibration if required.

Calibration is performed using a two-point method. The selected calibration points should be placed as close as possible to the minimum and maximum values of the measurement range.

Input Calibration

To calibrate the inputs, the user must apply known analog reference signals. For example, calibrating 4–20 mA inputs requires providing accurate 4 mA and 20 mA current sources.

Output Calibration

To calibrate the outputs, the user must:

  1. Issue a command to set the output to a desired value.
  2. Measure the actual output using a calibrated instrument.
  3. Issue the corresponding calibration command to store the measured value.

Storage and Reset

Calibration values are stored in non-volatile flash memory, and the input transfer curve is assumed to be linear.

If an incorrect command or value is entered during calibration, a RESET command can restore all channels in the selected group to their factory calibration values. After a reset, the calibration procedure can be repeated.

Calibration Without External Sources

The board can also be calibrated without external analog signal sources by:

  1. Calibrating the outputs first, and
  2. Routing the calibrated outputs to the corresponding input channels for input calibration.

The following firmware commands are available for performing calibration:

CALIBRATE 0-10V INPUTS:               multiio <id> uincal <channel> <value>
RESET CALIBRATION OF 0-10V INPUTS:    multiio <id> uincalrst <channel>
CALIBRATE 4-20mA INPUTS:              multiio <id> iincal <channel> <value>
RESET CALIBRATION OF 4-20mA INPUTS:   multiio <id> iincalrst <channel>
CALIBRATE 0-10V OUTPUTS:              multiio <id> uoutcal <channel> <value>
RESET CALIBRATION OF 0-10V OUTPUTS:   multiio <id> uoutcalrst <channel>
CALIBRATE 4-20mA OUTPUTS:             multiio <id> ioutcal <channel> <value>
RESET CALIBRATION OF 4-20mA OUTPUTS:  multiio <id> ioutcalrst <channel>

COMMUNICATION INTERFACES

RS485 / MODBUS

The Multi-IO HAT includes a standard RS-485 transceiver that can be accessed either by the onboard processor or by the Raspberry Pi. The operating mode is configured using the TX and RX switches on the DIP switch.

When TX and RX are set to ON, the Raspberry Pi communicates directly with any device that has an RS-485 interface. In this mode the card functions as a passive bridge, implementing only the hardware signal levels required by the RS-485 protocol. To use this configuration, the onboard processor must first release control of the RS-485 bus:

~$ multiio 0 cfg485wr 1 9600 1 0 1

When TX and RX are set to OFF, the card operates as a MODBUS RTU slave. Any MODBUS master — PLC, SCADA, or HMI — can read all inputs and control all outputs using standard MODBUS commands, with no Raspberry Pi required. A full list of supported MODBUS registers is available on GitHub.

In both modes, the onboard processor must be configured to either release or control the RS-485 signals accordingly. Refer to the command-line help for further details.

RS232

The Multi-IO HAT includes an RS232 serial port accessible only from the Raspberry Pi. It uses GPIO pins 32 (TX) and 33 (RX) of the GPIO connector. When the RS232 port is not in use, pin 33 (RX) can be disconnected with a jumper, freeing it for other functions.

HARDWARE WATCHDOG

The Multi-IO HAT includes a hardware watchdog that ensures your system automatically recovers if the Raspberry Pi software becomes unresponsive. The watchdog is disabled at power-up and activates after it receives the first reset command from the Raspberry Pi.

Watchdog Parameters
Initial timeout period Configurable — allows time for Raspberry Pi to boot and start the application
Running timeout period Configurable — normal operating timeout
Off period Configurable — duration the Raspberry Pi power is cut when timeout triggers
Reset counter Stored in non-volatile flash; can be read or cleared at any time

For a full list of watchdog commands, run: multiio -h

COMPATIBILITY

Interface I2C
GPIO used GPIO2 (SDA), GPIO3 (SCL) — 2 pins for I2C; GPIO8, GPIO10 optionally used for RS485 (DIP switch RX/TX); GPIO32, GPIO33 for RS232
Max stack 8 cards of each type; different Sequent HATs can be freely mixed with virtually no upper limit on total I/O
Compatible with All Raspberry Pi versions from Zero to 5 (40-pin GPIO header)

DOWNLOADS

User's Guide (PDF) Schematics (PDF) CAD Software & Integrations
User's Guide V1.3 Schematic V1.3 3D Printing Enclosure Command Line
Schematic V2.0 3D STEP Model V1.3 Python Library
CODESYS Driver
Home Assistant

COMPLIANCE

RoHS and REACH Compliance Declaration

WHAT'S INCLUDED

When you purchase the card you will receive the following items:

1. Multi-IO Card for Raspberry Pi
Multi-IO HAT for Raspberry Pi — 3D view
2. Mounting Hardware
Mounting hardware for Multi-IO HAT for Raspberry Pi
  • Four M2.5×18mm male-female brass standoffs
  • Four M2.5×5mm brass screws
  • Four M2.5 brass nuts
3. Connector Plugs for all Inputs and Outputs
Connector plugs for Multi-IO HAT for Raspberry Pi
  • Two 2-pin female mating connector plugs
  • Six 3-pin female mating connector plugs
  • One 4-pin female mating connector plug
  • One 5-pin female mating connector plug
  • One 7-pin female mating connector plug

QUICK START

  1. Plug your 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 software from GitHub:
    ~$ git clone https://github.com/SequentMicrosystems/multiio-rpi.git
    ~$ cd /home/pi/multiio-rpi
    ~/multiio-rpi$ sudo make install
    ~/multiio-rpi$ multiio

The program will respond with a list of available commands. To read more about the CLI, please refer to the README file. If you would rather use a different platform, you can access the same functionality through dedicated, ready-to-use integrations in the Downloads tab above.

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