Sixteen LV Digital Inputs 8-Layer Stackable HAT for Raspberry Pi (v3.0)

Raspberry Pi can read 26 Input signals through the GPIO header, but sometimes you might need to read more. Since all GPIO pins are wired directly to the local processor, some hardware is required to connect them to the real world.

This card has sixteen optically isolated Digital Inputs. Input ranges can be jumper-selected for each channel, from 3 volts to 48 volts. Digital Inputs can read both DC and AC signals.

The card communicates with Raspberry Pi using only the I2C port, leaving all the other 24 GPIO pins available for your use. It also has an RS-485 port, a power LED and a push button that can be used to shut down the Raspberry Pi. Pluggable connectors make the 16-INPUTS card easy to use when multiple cards are stacked up. 

For any technical questions about this product please email support@sequentmicrosystems.com

Features

• Sixteen LV Digital Inputs 8-Layer Stackable HAT for Raspberry Pi
• NEW FEATURES IN VERSION 3:
  • *NEW*: Local processor permits standalone operation (no Raspberry Pi)
  • *NEW*: Hardware watchdog resets Raspberry Pi in case of software lockup
  • *NEW*: 3 PIN RS385 Connector
  • *NEW*: 8 extra LEDs (total 16 LEDs, one for each input)
  • *NEW*: DIP Switch Stack Level and RS485 selection (no more jumpers)
• Inputs can be accessed from any PLC using RS485/MODBUS
• Sixteen LV Digital Inputs 8-Layer Stackable HAT for Raspberry Pi
• All inputs opto-isolated reading 3V-48V AC/DC
• Eight-layer stackable to 128 inputs
• Can interrupt Raspberry Pi on any change of input (no need for polling)
• Pluggable Connectors 26-16 AWG wires
• RS485/MODBUS port
• 16 LEDs showing status of each input
• General purpose push-button
  
• Sixteen LV Digital Inputs for Raspberry Pi
• Uses only I2C port, all GPIO pins available
• Works with any Raspberry Pi from ZERO to 5
• ECCN Code EAR99
• Operating temperature range: -40 to +85  °C
• Storage temperature range:  –65 to +150 °C
• Command Line Driver 
• Python Library
• Node-Red nodes
• CODESYS Driver
• OpenPLC module
• CODESYS Library
• Home Assistant Integration
  

Compatibility

The card is compatible with all Raspberry Pi versions from Zero to the Pi 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 card needs 5V to operate and can be powered from the Raspberry Pi or from its own 2-pin pluggable connector. The card draws 10mA. If power is applied to the 2-pin pluggable connector, no other power supply is needed for the Raspberry Pi.

LED Indicators

Stacking Multiple Cards

Up to eight 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. A three-position jumper selects the stack level.

Reset Pushbutton

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 power 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 that monitors this pin, and if pressed for more than the desired time, issues the shut-down command.

RS485 Port

An RS485 transceiver enables the Raspberry Pi to connect to other industrial sensors or actuators. In order to use the RS485 port, a jumper needs to be installed on the RXD line going to Raspberry Pi. The jumper is marked RS485 in the layout below. If the jumper is not installed, the RXD line from Raspberry Pi can be used as GPIO.

DIN-Rail Mounting

The card can be installed parallel on a DIN-Rail using the DIN-Rail Kit Type 1, or perpendicular using the DIN-Rail Kit Type 2. Shown here is a perpendicular installation which can be expanded to 8 cards.

Resources

• Product documentation site

Software Interfaces

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. Examples are provided at GitHub.

Quick Start

• Plug your 16-INPUTS card on top of your Raspberry Pi and power up the system.
• Enable I2C communication on Raspberry Pi using raspi-config.
• Install the card software from github.com:

~$ git clone https://github.com/SequentMicrosystems/16inpind-rpi.git
~$ cd /home/pi/16inpind-rpi
~/16inpind-rpi$ sudo make install
~/16inpind-rpi$ 16inpind -h
The program will respond with a list of available commands.

Electrical Specifications

• Power Supply: 5V/8A pluggable connector with reverse polarity protection
• On board resettable fuse: 3A
• Opto-isolated Digital Inputs:
• Input Forward Current: Typical 5 mA, maximum 50 mA
• Low Voltage Input Series Resistor: 2.2K
  
• Isolation Voltage between inputs and ground: 5,000Vrms

Package Contents

• 1x 16-inputs card for Raspberry Pi
• Four M2.5x18mm male-female brass standoffs
• Four M2.5x5mm brass screws
• Four M2.5 brass nuts
• Mating connector plugs

Revision History

• As of 09/12/2024 - We are now stocking board version v3.0
• As of 01/11/2022 we are now offering an updated version from Sequent which no longer offers jumper-selectable higher voltage input ranges (as well as some PCb layout changes)