Sixteen Relays 2A 24V 8-layer stackable HAT for Raspberry Pi with DIP switches and pluggable connectors.

Sixteen Relays 2A/24V 8-layer stackable HAT module with status LEDs and DIP switch for Raspberry Pi control

Sixteen Relays 2A 24V 8-layer stackable HAT with status LEDs and pluggable connectors for Raspberry Pi.

Sixteen Relays 2A/24V 8-layer stackable HAT module for Raspberry Pi with status LEDs and pluggable connectors.

Sixteen Relays 2A 24V 8-layer stackable HAT circuit board for Raspberry Pi with labeled connectors and integrated components.

SKU: SM-I-013

Sixteen Relays 2A/24V 8-Layer Stackable HAT for Raspberry Pi

Name: Sixteen Relays 2A/24V 8-Layer Stackable HAT for Raspberry Pi
Brand: Sequent Microsystems
SKU: SM-I-013
Price: 80.0 USD
Availability: InStock

Sixteen relays with status LEDs and Normal Open contacts; RS485 and Hardware Watchdog.

In stock

$80.00

Product variants

Overview

Sixteen-relay HAT for Raspberry Pi with stackable design for high-density load control. Sixteen normally-open relay contacts, bicolor status LEDs, RS485/MODBUS interface, and a hardware watchdog in a compact, stackable platform for industrial and building automation applications.

Sixteen NO relay contacts rated 2A/24VAC/DC
Eight bicolor status LEDs show the on/off state of all 16 relays
Up to 8 cards stackable — 128 relays per Raspberry Pi
RS485/MODBUS port for direct PLC/SCADA integration
Hardware watchdog ensures continuous unattended operation
Uses only I2C — all 24 remaining GPIO pins stay free
Compatible with all Raspberry Pi versions from Zero to 5

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 Relay Outputs (NO contacts, 2A/24VAC/DC)	• I2C Port to Raspberry Pi	• Command Line
	• RS485/MODBUS Port	• Python Library
		• Node-RED nodes
		• CODESYS Driver
		• OpenPLC Module
		• Home Assistant
		• Arduino Library
Other Features
• Software relay self-test cycles all relays on and off at 0.5-second intervals
• Eight bicolor status LEDs show the on/off state of all 16 relays
• 5V onboard power supply also powers the Raspberry Pi
• General purpose reset pushbutton (GPIO 26)	• Pluggable Connectors 26–16 AWG wires
• On Board Hardware Watchdog and resettable fuse	• Eight Level Stackable

DESCRIPTION

The Sixteen Relays HAT provides a simple and scalable way to control large numbers of loads with Raspberry Pi. Stackable to 8 layers, a single Raspberry Pi can manage up to 128 relays in a compact, modular form factor.

Relay Outputs

Sixteen normally-open relay contacts rated 2A/24VAC/DC, connected via pluggable screw terminals. Electrical endurance: minimum 10⁵ cycles at full load; mechanical endurance: minimum 10⁷ cycles.

Status LEDs

Eight bicolor LEDs show the on/off state of all 16 relays — one color per relay per LED. A dedicated power LED confirms when the board is powered.

Hardware Watchdog

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

RS485 / MODBUS

Onboard RS485 port configurable as a MODBUS RTU slave — accessible by any PLC or SCADA without a Raspberry Pi — or as a direct RS485 bridge for the Raspberry Pi, via DIP switch.

Reset Pushbutton

A momentary pushbutton at the board edge routes to GPIO 26. A user script monitoring this pin can issue a clean shutdown command, preventing SD card corruption from hard power cuts.

Relay Self-Test

A single command cycles each relay on and off at 0.5-second intervals. The relay clicking and LED activity confirm all 16 relays are functional before deployment.

Protection

An onboard 3A resettable fuse protects against accidental shorts on the power supply.

TECHNICAL DETAILS

CARD LAYOUT

Sixteen Relays 2A/24V 8-Layer Stackable HAT for Raspberry Pi — board layout

MECHANICAL SPECIFICATIONS

Sixteen Relays 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/8A pluggable connector with reverse polarity protection
Power consumption (relays off)	10 mA
Power per relay (energized)	~80 mA
Onboard resettable fuse	3 A

Relay Outputs
Contact type	Normally Open (NO)
Contact rating	2A / 24VAC/DC
Electrical endurance	Min. 10⁵ cycles at 1,800 operations/hour, full load
Mechanical endurance	Min. 10⁷ cycles at 18,000 operations/hour, no load

POWER REQUIREMENTS

Power supply: The card requires 5V to operate and can be powered from the Raspberry Pi GPIO or from its own 2-pin pluggable connector. If power is applied to the board's connector, no separate Raspberry Pi power supply is needed. The board draws 10mA with all relays off; each relay coil requires approximately 80mA when energized.

PLUGGABLE CONNECTORS

All relay outputs connect via 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 Relays 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:

~$ 16relind 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 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.

RESET PUSHBUTTON

Shutting down the Raspberry Pi by turning off the power can result in SD card failure. To prevent this, a shutdown command must be issued before cutting power — but that normally requires a monitor, keyboard, and mouse connected to the Pi.

A momentary pushbutton installed at the edge of the Sixteen Relays card provides a convenient way to shut down the Raspberry Pi. The button is routed to pin 37 (GPIO 26). Write a script that monitors this pin and, if held for more than a desired duration, issues the shutdown command.

HARDWARE WATCHDOG

The Sixteen Relays 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. The default running timeout is 120 seconds and the off period is 10 seconds; both are configurable from the command line.

Watchdog Parameters
Initial timeout period	Configurable — allows time for Raspberry Pi to boot and start the application
Running timeout period	Configurable — normal operating timeout (default: 120 seconds)
Off period	Configurable — duration the Raspberry Pi power is cut when timeout triggers (default: 10 seconds)
Reset counter	Stored in non-volatile flash; can be read or cleared at any time

For a full list of watchdog commands, run: 16relind -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 ~/16relind-rpi/update/

~/16relind-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/16relind-rpi/tree/master/update/README.md

DOWNLOADS

User's Guide (PDF)	Schematics (PDF)	CAD	Software & Integrations
User's Guide V1.0	Hardware Schematic V2.0	3D Printing Enclosure	Command Line
	Hardware Schematic V4.1	2D CAD Drawing	Python Library
		V4.1 3D STEP Model	Node-RED nodes
			MODBUS interface
			CODESYS Library
			Home Assistant
			Arduino Library

COMPLIANCE

RoHS and REACH Compliance Declaration

WHAT'S INCLUDED

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

1. Sixteen Relays HAT 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 Relay 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/16relind-rpi.git

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

~/16relind-rpi$ sudo make install

~/16relind-rpi$ 16relind

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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Very Easy to get working, impressive support!

I got this so I could control relays with a custom program, and I found the documentation and sample programs on the product page on the Sequent Microsystem website very helpful. I don't mind the shared commons, but I can see how that could be an issue for some applications, I can see why they did that though, because jamming 16 relays on a Raspberry Pi HAT is not easy to do. The I2C interface is GREAT! It leaves all my GPIO for other uses, and the boards are properly stackable, which is not always the case with Raspberry Pi relay boards.

The customer support is EXCELLENT, and the product listing on the Sequent Microsystems website is really above and beyond what is normally available for this kind of product! It includes source code to control it from multiple options like python, command line, node-red and even Arduino, even though it's for Raspberry Pi, you could wire it to an Arduino and if you do, they give you the library to run it! Not only that, but what's really impressive, is they have 2D Cad files, and 3D Solid models of the board! So, you can very easily design a case to go neatly around all the connectors, etc. I'm very impressed with the level of detail and the wealth of resources available on the Sequent Microsystems website!

They also have this exact same board with Solid State relays, and I was VERY happy to find out the solid state relays work like true relays, being able to control both AC and DC loads, so if you have an application that requires a lot of switching that would wear out a mechanical relay, the solid state relay version is definitely the way to go!

I found this very easy to get working, just plugged it onto my pi and I had it controlling relays in a matter of just a few minutes. I wish all the manufactures of Raspberry Pi and Arduino boards had the level of information that Sequent Microsystems has available for this board!

Fantastic products, even better support!

I am fairly new to Raspberry Pi, and I am happy I found Sequent. The products are top notch... I now have 2 of the 8-hat relays, (1) 16 hat relay, (1) Building Automation hat, and (2) of the fans.
The only thing I can say that is more positive than their products is their support. You cant find service like they offer much anymore... and it is very appreciated!

If there is something you need or that can help make the product better, hit them up on chat... they respond very quickly and they actually listen.
Thanks Sequent!

Great idea (I2C control 16 relays on 1 card), works perfect and more.

Good useful product,
People who stand behind the product,
Great customer service.
Its a trifecta !

Works fantastically, software improvments delivered quickly

Great product works exactly as advertised. They even promptly put the python library on pypi for easier installation with pip on request. Highly recommend for any generic low frequency controlling needs.

Support == Awesome!!

The board works great with codesys so far with a modified library/device file.

The boards were out of stock and the team at Sequent Microsystems went out of the way to get us some ASAP and the whole communication was exceptionally well!!

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