SENSORS/ACTUATORS

Arduino - Car

Arduino - Measure Voltage

Arduino - Force Sensor

Arduino - Infrared Obstacle Avoidance Sensor

Arduino - GPS

Arduino - IR Remote Control

INTERNET OF THING (IoT)

LIBRARIES

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:

A 4-channel relay module has simpler wiring.
A 4-channel relay module uses less space.
A 4-channel relay module is cheaper.
The programming is the same.

Hardware Required

1	×	Arduino UNO or Genuino UNO
1	×	USB 2.0 cable type A/B (for USB-A PC)
1	×	USB 2.0 cable type C/B (for USB-C PC)
1	×	4-channel Relay Module
1	×	Jumper Wires
1	×	(Recommended) Screw Terminal Block Shield for Arduino Uno
1	×	(Recommended) Breadboard Shield For Arduino Uno
1	×	(Recommended) Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some links in this section are Amazon affiliate links. If you make a purchase through these links, we may earn a commission at no extra cost to you.
Additionally, some links direct to products from our own brand, DIYables.

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

This image is created 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

This image is created 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);

Control the relay's state by using digitalWrite() function.

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

See the best Arduino kit for beginner

See Also

※ OUR MESSAGES

We are AVAILABLE for HIRE. See how to hire us to build your project

If this tutorial is useful for you, please give us motivation to make more tutorials.
You can share the link of this tutorial anywhere. Howerver, please do not copy the content to share on other websites. We took a lot of time and effort to create the content of this tutorial, please respect our work!