Arduino - 4-Channel Relay Module

When we want to control 4 high-voltage devices such as pumps, fans, actuators... We can use multiple relay modules. However, there is a simpler way is to use a 4-channel relay module. A 4-channel relay module is a combination of 4 relays on a single board.

A 4-channel relay module vs 4 x 1-channel relay modules:

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×4-Channel Relay Module
n×Jumper Wires
Please note: These are affiliate links. If you buy the components through these links, We may get a commission at no extra cost to you. We appreciate it.

About 4-Channel Relay Module

Pinout

4-Channel Relay Module Pinout

A 4-channel relay module has the following pins:

  • Power pins for relay boards
    • DC+ connect this pin to 5V pin of power supply
    • DC- connect this pin to the GND pin of the power supply and also to the GND pin of the Arduino
  • Signal pins:
    • IN1 this pin receives the control signal from Arduino to control relay 1 on the module
    • IN2 this pin receives the control signal from Arduino to control relay 2 on the module
    • IN3 this pin receives the control signal from Arduino to control relay 3 on the module
    • IN4 this pin receives the control signal from Arduino to control relay 4 on the module
  • Output pins NCx (normally closed pin), NOx (normally open pin), COMx (common pin),
    • NC1, NO1, COM1 These pins connect to a high-voltage device that is controlled by relay 1
    • NC2, NO2, COM2 These pins connect to a high-voltage device that is controlled by relay 2
    • NC3, NO3, COM3 These pins connect to a high-voltage device that is controlled by relay 3
    • NC4, NO4, COM4 These pins connect to a high-voltage device that is controlled by relay 4

For detail of how to connect relay to high-voltage, what are differences between normally closed and normally open, see Arduino - Relay tutorial

It also has 4 jumpers to select between the low trigger and the high trigger for each relay individually.

Wiring Diagram

4-channel relay module consumes considerable power. Therefore, we should NOT power the module directly from the 5V pin of Arduino. We need to use external 5V power for the module instead.

So, we need to use three power sources:

  • A 5V power adapter for Arduino
  • A 5V power adapter for the 4-channel relay module
  • A higher-voltage power adapter (12VDC, 24VDC, 48VDC, 220AC...) for things that are controlled by the 4-channel relay module
  • Wiring diagram with three power sources. Power supply for Arduino (not included in the image) can be via either USB cable or power jack.
  • Arduino 4-channel relay module wiring diagram

    Image is developed using Fritzing. Click to enlarge image

  • We can reduce the number of power adapters by using a single 5V power source for both Arduino and the 4-channel relay module.
  • Arduino 4-channel relay module wiring diagram two power source

    Image is developed using Fritzing. Click to enlarge image

※ NOTE THAT:

If 4 devices that are controlled by a 4-channel relay module use the same voltage, we can use a single high-voltage power adapter for all. However, if they use different voltages, we can use different high-voltage power adapters independently.

How To Program For 4-Channel Relay Module

  • Initializes the Arduino pin to the digital output mode by using pinMode() function.
pinMode(PIN_RELAY_1, OUTPUT); pinMode(PIN_RELAY_2, OUTPUT); pinMode(PIN_RELAY_3, OUTPUT); pinMode(PIN_RELAY_4, OUTPUT);
digitalWrite(PIN_RELAY_1, HIGH); digitalWrite(PIN_RELAY_2, HIGH); digitalWrite(PIN_RELAY_3, HIGH); digitalWrite(PIN_RELAY_4, HIGH);

Arduino Code

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-4-channel-relay-module */ #define PIN_RELAY_1 2 // the Arduino pin, which connects to the IN1 pin of relay module #define PIN_RELAY_2 3 // the Arduino pin, which connects to the IN2 pin of relay module #define PIN_RELAY_3 4 // the Arduino pin, which connects to the IN3 pin of relay module #define PIN_RELAY_4 5 // the Arduino pin, which connects to the IN4 pin of relay module // the setup function runs once when you press reset or power the board void setup() { Serial.begin(9600); // initialize digital pin as an output. pinMode(PIN_RELAY_1, OUTPUT); pinMode(PIN_RELAY_2, OUTPUT); pinMode(PIN_RELAY_3, OUTPUT); pinMode(PIN_RELAY_4, OUTPUT); } // the loop function runs over and over again forever void loop() { Serial.println("Turn on all"); digitalWrite(PIN_RELAY_1, HIGH); digitalWrite(PIN_RELAY_2, HIGH); digitalWrite(PIN_RELAY_3, HIGH); digitalWrite(PIN_RELAY_4, HIGH); delay(1000); Serial.println("Turn off all"); digitalWrite(PIN_RELAY_1, LOW); digitalWrite(PIN_RELAY_2, LOW); digitalWrite(PIN_RELAY_3, LOW); digitalWrite(PIN_RELAY_4, LOW); delay(1000); }

Quick Steps

  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
  • Listen the click sound on relays.
  • See the result on Serial Monitor.
  • COM6
    Send
    Turn on all Turn off all Turn on all Turn off all Turn on all Turn off all Turn on all Turn off all
    Autoscroll Show timestamp
    Clear output
    9600 baud  
    Newline  

Video Tutorial

We are considering to make the video tutorials. If you think the video tutorials are essential, please subscribe to our YouTube channel to give us motivation for making the videos.

Function References

The Best Arduino Starter Kit

※ OUR MESSAGES