Sixteen LV Digital Inputs stackable HAT with RS485 and DIP switches for Raspberry Pi V3.0

Sixteen LV Digital Inputs 8-layer stackable HAT with opto-isolated inputs and RS485 for Raspberry Pi.

Sixteen LV Digital Inputs stackable HAT with opto-isolated inputs and DIP switches for Raspberry Pi.

Sixteen LV Digital Inputs 8-layer stackable Raspberry Pi HAT with opto-isolated inputs, DIP switch, and RS485 port

Sixteen LV Digital Inputs stackable HAT board for Raspberry Pi with 16 opto-isolated digital inputs and I2C interface

SKU: SM-I-009

Sixteen LV Digital Inputs 8-Layer Stackable HAT for Raspberry Pi

Name: Sixteen LV Digital Inputs 8-Layer Stackable HAT for Raspberry Pi
Brand: Sequent Microsystems
SKU: SM-I-009
Price: 55.0 USD
Availability: InStock

Sixteen 3V-24V Opto-isolated Inputs with LED indicators; RS485/MODBUS, Hardware Watchdog.

In stock

$55.00

Product variants

Overview

Add sixteen opto-isolated digital inputs to any Raspberry Pi (Zero–5) with this 8-layer stackable HAT. The Sixteen LV Digital Inputs Card reads 3–24 V AC/DC signals, includes a hardware watchdog and local processor for standalone operation, and connects to any PLC or SCADA via RS485/MODBUS — all over I²C, leaving every other GPIO pin free.

Sixteen opto-isolated digital inputs, 3–24 V AC/DC (reads both AC and DC)
Native RS485 / MODBUS interface
Hardware watchdog for unattended operation
Interrupt-on-change on any input — no polling required
Up to 8 cards can be stacked for 128 inputs total
Uses only I²C — all other GPIO pins stay free

Works with Open Automation Software

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

INTERFACES AND I/O

I/O's	Communication	Software Integration
• Sixteen Opto-Isolated Digital Inputs (3–24 V AC/DC)	• I2C Port to Raspberry Pi	• Command Line
	• RS485/MODBUS Port	• Python Library
		• Node-RED nodes
		• CODESYS Driver
		• OpenPLC Module
		• Home Assistant
Other Features
• Interrupt-on-change on any input — no polling required
• 16 LEDs, one per input, plus power LED
• General purpose shutdown push-button	• Pluggable Connectors 26-16 AWG wires
• On Board Hardware Watchdog and fuse	• Eight Level Stackable — up to 128 inputs

DESCRIPTION

The Sixteen LV Digital Inputs Card provides a reliable, scalable way to bring sixteen industrial-grade digital signals into any Raspberry Pi system.

Digital Inputs

Sixteen optically isolated digital inputs read signals from 3 V to 24 V AC or DC, suitable for industrial sensors, limit switches, PLCs, and building automation signals.

Interrupt on Change

The card can interrupt the Raspberry Pi on any input state change, eliminating the need for continuous polling and enabling fast, event-driven response to field signals.

LED Status Indicators

Sixteen LEDs show the live status of every input channel, plus a dedicated power LED. Field diagnostics are immediate without needing a connected computer.

RS485 / MODBUS

A standard RS485 transceiver enables the card to act as a MODBUS RTU slave for direct PLC or SCADA access, or as a hardware pass-through for the Raspberry Pi serial port.

Hardware Watchdog

The hardware watchdog automatically power-cycles the Raspberry Pi if the software becomes unresponsive, ensuring continuous operation in unattended deployments.

Shutdown Push-Button

A momentary push-button wired to GPIO 26 provides a safe way to issue a software shutdown command without a keyboard or monitor, preventing SD card corruption on power-off.

Stackable Design

Up to eight cards can be stacked on any Raspberry Pi, scaling to 128 inputs. The card uses only I²C (GPIO2, GPIO3); all other GPIO pins remain available for other uses.

TECHNICAL DETAILS

CARD LAYOUT

Sixteen LV Digital Inputs Card board layout showing connector positions, DIP switch, and GPIO header for Raspberry Pi

MECHANICAL SPECIFICATIONS

Sixteen LV Digital Inputs Card 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

ELECTRICAL SPECIFICATIONS

Power
Power supply	5V from Raspberry Pi GPIO or 2-pin pluggable connector
Power consumption	10 mA
Onboard resettable fuse	3 A

Opto-Isolated Digital Inputs
Input voltage range	3–24 V AC/DC
Input Forward Current	Typical 5 mA, maximum 50 mA
Input Series Resistor	2.2 KΩ
Isolation Voltage	5,000 Vrms

POWER REQUIREMENTS

Power supply: The card is powered from the Raspberry Pi GPIO header (5V) or from its own 2-pin pluggable connector. Operating current is 10 mA. If the 2-pin connector is used, no separate Raspberry Pi power supply is needed.

PLUGGABLE CONNECTORS

All I/Os connect to 3.5mm pitch pluggable screw terminal connectors, accepting wire gauges from 26 to 16 AWG. Connectors can be unplugged from the board for convenient field wiring and debugging without disturbing the rest of the installation.

COMMUNICATION INTERFACES

RS485 / MODBUS

The Sixteen LV Digital Inputs Card 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:

~$ 16inpind 0 rs485wr 0 0 0 0 0

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 16 inputs 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.

HARDWARE WATCHDOG

The Sixteen LV Digital Inputs Card 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: 16inpind -h

COMPATIBILITY

Interface	I2C
GPIO used	GPIO2 (SDA), GPIO3 (SCL) — 2 pins only; remaining 24 GPIO pins stay free
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)

FIRMWARE UPDATE

The onboard microcontroller firmware can be updated in the field. The update tool downloads the latest firmware from Sequent Microsystems' servers and flashes it to the board over I2C.

WARNING: Stop all processes that access the card (Node-RED flows, Python scripts, cron jobs) before starting a firmware update. Accessing the card during an update may corrupt the firmware.

Running the Update

~$ cd ~/16inpind-rpi/update/

~/16inpind-rpi/update$ ./update <id>

Replace <id> with the board stack address (0-7). Full instructions including recovery procedures are available at:

https://github.com/SequentMicrosystems/16inpind-rpi/tree/master/update/README.md

DOWNLOADS

User's Guide (PDF)	Schematics (PDF)	CAD	Software & Integrations
User's Guide	Schematic V2.0	2D CAD Drawing V2.0	Command Line
	Schematic V3.0	3D STEP Model V3.0	Python Library
		3D Printing Enclosure	Node-RED nodes
			MODBUS interface
			CODESYS Library
			Home Assistant

COMPLIANCE

RoHS and REACH Compliance Declaration

WHAT'S INCLUDED

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

1. Sixteen LV Digital Inputs Card for Raspberry Pi

2. Mounting Hardware
	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
	Two 2-pin female mating connector plugs Nine 3-pin female mating connector plugs

QUICK START

Plug your card on top of your Raspberry Pi and power up the system.
Enable I2C communication on Raspberry Pi using raspi-config.
Install the software from GitHub:

~$ git clone https://github.com/SequentMicrosystems/16inpind-rpi.git

~$ cd /home/pi/16inpind-rpi

~/16inpind-rpi$ sudo make install

~/16inpind-rpi$ 16inpind

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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Lots if inputs, nice event-based notification in NodeRed!

My greenhouse application for this board (Raspberry PI 5) utilizes Sequent's NodeRed plugin for event-based flows.

This is apparently a newer feature of the board/software which take advantage of a shared interrupt used by all Sequent hats.

As has always been the case, support is super responsive and super helpful whenever needed! Like the quality of the cards themselves, support in my experience has been top notch.

We ensured the latest firmware (1.05 at the time) was applied, the GPIO node added to signal the interrupt had occurred, and also that GPIO was configured to the appropriate values (GPIO 26, pull-up, 5ms de-bounce worked well)

Interrupt was enabled in my application for all inputs using command 16inpind [stack level] optintwr 65535. Note this needed to be reapplied after the firmware update.

Additional documentation may be an opportunity. That didn't slow my progress much however given the high level of support received. All up and working in a few hours.

These boards continue to be a great value. Highly recommend Sequent

Sixteen LV Digital Inputs 8-Layer Stackable HAT for Raspberry Pi

Lots of optoisolated inputs and RS485 port

If you need to read many inputs with your Pi, this is the best solution. Up to 128 opto-isolated inputs which you can read even without a Raspberry Pi, using MODBUS and a standard PLC. Great HAT

works good

it has been working good.

Wonderful integration for 12V alarm sensors

I used this board to integrate my wired 12V alarm sensors into a custom alarm system built with HomeAssistant (the Raspberry is publishing readings through MQTT).
The board is using I2C to communicate with the Raspberry and I had some issue with that. The support has been exceptional and provided me good advices. My problem turned out to be an HW issue on the Raspberry side.
Since I replaced the faulty Raspberry I had no more any issue.

One thing to point out is that there is a nice (undocumented) feature: the I/O expander chip is able to provide an interrupt to the Raspberry over GPIO11 whenever one of the input changes state. This makes it possible to write an interrupt-based (vs poll-based) logic on the Raspberry.

I also want to mention that the plug-in connectors are really good because they make it possible to easily unplug a particular input without imposing mechanical stress on the whole board.

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