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

Pluggable connectors make the card easy to use when multiple cards are stacked up. Relays have N.O. contacts and can switch 24V/2A AC/DC.

Bicolour LEDs conveniently grouped on one side of the board show when relays are on or off. A power LED shows when power is applied. A reset switch permits shutting down the Raspberry Pi without the use of a keyboard and monitor.

Compatibility

The card is compatible with all Raspberry Pi boards from Zero to 4. All stacked cards share the I2C bus using only two of the Raspberry Pi’s GPIO pins to manage all eight cards. This feature leaves the remaining 24 GPIOs available for the user.

Power requirements

The 16-RELAY card needs 5V to operate and can be powered by the Raspberry Pi or from its own 2-pin pluggable connector.

The relay coils are also powered by the 5V line. The card draws 10mA with all relays off. Each relay needs about 80 mA to turn on. If power is applied to the board's connector, no other power supply is needed for the Raspberry Pi.

LED Indicators

A power LED shows when power is applied to the board. Due to space limitations, bicolour LEDs are used to show the status of groups of 8 relays.

Stacking Multiple Cards

Up to eight of these cards can be stacked on your Raspberry Pi. Each card is identified by jumpers you install to indicate the level in the stack. Cards can be installed in any order. The three-position jumper selects the stack level.

For your convenience, two jumpers are provided with each card. For complex Home Automation tasks, you can add to the stack one or more Home Automation cards with analog and digital inputs and outputs.

Reverse Power Supply Protection

The board is protected from an accidental reverse power supply with a 5.8A 39 mOhm MOSFET which breaks the ground line if reverse power is applied.

Reset Button

Shutting down the Raspberry Pi by turning off the power can result in SD Card failure. To prevent this, a shutdown command needs to be used before the power is cut-off. But this requires a monitor, keyboard and mouse connected to the Pi.

A momentary push-button installed at the edge of the board provides a convenient way to shut down the Raspberry Pi. The button is routed to pin 37 (GPIO 26). You need to write a script which monitors this pin, and if pressed for more than a desired time, issues the shut-down command.

Features

• Sixteen Relays 2A/24V 8-Layer Stackable HAT
• All Relays with Status LEDs and NO contacts
• Eight-layer stackable (up to 128 relays)
• Pluggable Connectors 26-16 AWG wires
• 24V/2A AC/DC on relay contacts
• RS485 Port
• General purpose push-button
• 8 LEDs showing the status of groups of 8 relays
• Software self-test
• Sixteen Relays Raspberry Pi
• Command Line
• Python Library
• Node-Red nodes
• OpenPLC module

Specifications

Electrical

• Power Supply: 5V/8A pluggable connector with reverse polarity protection
• On board resettable fuse: 3A
• Relays: NO contacts, 2.5A/24 VAC/DC
• Electrical endurance: minimum 10(5) cycles at 1,800 operations per hour, full load
• Mechanical endurance: minimum 10(7) cycles at 18,000 operations per hour, no load

Resources

• SIXTEEN Relays Downloads
• Command Line
• Python Library
• Node-Red nodes
• OpenPLC module

Software

Interfaces

You can write your own application using the Command Line or Python Libraries 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. Examples are provided at GitHub.

Relay Self-test

The card can be tested before installation by running a simple command from the command line. The card will cycle each relay on and off at 0.5 seconds intervals. The clicking noise of the relays and the lighting of the LEDs will assure that all relays are functioning.

Package Contents

• 1x 16-Relay HAT
• Pluggable connectors
• Fixings/standoffs