# 16 Channel I2C Relay Output Module

16 channel I2C relay output module based on the MCP23017

- **Seller:** [EA Control Tech](https://lectronz.com/stores/eacontroltech), Oakland, California, United States
- **Price:** $45.00 (USD, before shipping and taxes)
- **Availability:** In stock
- **Categories:** Application, Equipment, Platform
- **Country of origin:** United States
- **Product page:** https://lectronz.com/products/-16-channel-i2c-relay-output-module

## Links

- [Documentation](https://eacontroltech.com/16_DO_MCP23017.pdf)
- [Schematics](https://eacontroltech.com/16_DO_MCP23017_Schematic.pdf)

## Images

![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjcsInB1ciI6ImJsb2JfaWQifX0=--f0cb69c1f7c127e84cd5799b606d4a70a68c60df/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-26T04_08_36.207Z-16_DO_MCP23017_1..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjgsInB1ciI6ImJsb2JfaWQifX0=--a2874df0695504494e37c2fc0deaf0b75ac3294b/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T02-05-43.170Z-16_DO_MCP23017_3..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjksInB1ciI6ImJsb2JfaWQifX0=--830fa946dac73551acd3f884247b01e4561a3b58/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T02-05-43.170Z-16_DO_MCP23017_2..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MzAsInB1ciI6ImJsb2JfaWQifX0=--dc2e7e35fccf7cf3bf3f1db5405f56f9b41dead4/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T02-05-43.170Z-16_DO_MCP23017_4..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MzEsInB1ciI6ImJsb2JfaWQifX0=--c31bf40cbe038955a71b8686d8d5a46b4aee592e/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T02-05-43.170Z-16_DO_MCP23017_5..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MzIsInB1ciI6ImJsb2JfaWQifX0=--1582e00e642f80f14a4ef7404a1f95611a2a496a/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T02-05-43.170Z-16_DO_MCP23017_7..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MzMsInB1ciI6ImJsb2JfaWQifX0=--6b9ace18dc97a6bcb73c232a1adcbfd5832f8fb1/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T02-05-43.170Z-16_DO_MCP23017_6..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MzQsInB1ciI6ImJsb2JfaWQifX0=--f556747a341ad9b95229a0a1e82fae5a25438018/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T02-05-43.170Z-16_DO_MCP23017_8..jpeg)
![16 Channel I2C Relay Output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MzUsInB1ciI6ImJsb2JfaWQifX0=--8bf2c06c79414d2ffcded06f4fbb2fdeb1b4c6e4/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJwbmciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--605f1da017bcbb03ce31845cd0e81d97e3b3c574/2026-04-25T02-14-55.255Z-_16_DO_Board_MCP23017_Front_2.png)

## Description

**What is it?**

This is a 16-channel industrial relay output module designed for 24VDC control systems, based on the MCP23017 I2C GPIO expander.

It allows a microcontroller or PLC to control high-power AC or DC loads through integrated relay outputs, making it ideal for real-world automation and control applications.

Each output is driven through opto-isolated circuitry and transistor drivers, ensuring reliable operation and proper separation between logic and field signals.

**Why this board is different**

Most GPIO output boards:
- Only provide low-voltage logic outputs (3.3V / 5V)
- Cannot directly drive real loads
- Require external relays or driver circuits

This module provides a complete solution:
- Integrated relay outputs (no external drivers needed)
- 24VDC system compatibility
- Optocoupler-driven control for signal integrity
- Designed for industrial environments

👉 You can directly control real devices such as relays, solenoids, lamps, and contactors without additional interface hardware

**Key Features**
- 16 × relay outputs (SPST normally open)
- MCP23017 I2C GPIO expander
- Optocoupler-driven relay control
- 24VDC power input
- On-board 24V → 3.3V regulator
- Output status LEDs
- Flyback protection for relay coils
- Configurable I2C address (up to 8 modules)
- Interrupt outputs (INTA / INTB)
- Reset signal access
- I2C IN / OUT connectors for daisy-chaining
- Optional onboard I2C pull-ups
- Industrial screw terminal connectors

**Electrical Characteristics**
- Supply voltage: 24VDC nominal
- Logic interface: I2C (3.3V)
- Number of outputs: 16
- Relay type: SPST Normally Open
- Max load current: 5A per channel
- Max load voltage:
- 30VDC
- 250VAC
- Coil voltage: 24VDC
- Coil current: ~8.3 mA per relay

**Typical Applications**
- PLC and embedded controller output expansion
- Industrial automation systems
- Relay and contactor control
- Solenoid and actuator driving
- Alarm and signaling systems
- Remote / distributed I/O systems

**Integration**
- Control outputs via I2C interface
- Daisy-chain multiple modules (up to 8 boards)
- Compatible with STM32, ESP32, and other microcontrollers

Each output can directly switch external loads without additional circuitry.

**How it works**

When a GPIO output is activated:

Optocoupler turns ON
Driver stage energizes relay coil
Relay contact closes → load is powered

When deactivated:

Relay opens → load is disconnected

This architecture provides reliable switching and isolation between control logic and field devices

**Important Notes**
- Designed for 24VDC industrial control systems
- Suitable for switching AC and DC loads
- Use proper wiring and load ratings
- Disconnect power before modifying connections
- Ensure loads do not exceed relay ratings