Arduino Nano - 4-Channel Relay Module

When we need to control 4 high-voltage devices such as pumps, fans, actuators... We have the option of using multiple relay modules. Alternatively, there is a simpler solution: a 4-channel relay module. This is a single board that contains 4 relays.

A 4-channel relay module compared to 4 x 1-channel relay modules:

Its wiring is simpler.
It takes up less space.
It is more cost-effective.
The programming remains the same.

Hardware Preparation

1	×	Arduino Nano
1	×	USB A to Mini-B USB cable
1	×	4-channel Relay Module
1	×	Jumper Wires
1	×	Breadboard
1	×	(Recommended) Screw Terminal Expansion Board for Arduino Nano
1	×	(Recommended) Breakout Expansion Board for Arduino Nano

Or you can buy the following sensor kits:

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

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.

Overview of 4-Channel Relay Module

The 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 Nano

Signal pins:

IN1: this pin receives the control signal from Arduino Nano to control relay 1 on the module
IN2: this pin receives the control signal from Arduino Nano to control relay 2 on the module
IN3: this pin receives the control signal from Arduino Nano to control relay 3 on the module
IN4: this pin receives the control signal from Arduino Nano 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 link to a high-voltage device that is controlled by relay 1
NC2, NO2, COM2: These pins link to a high-voltage device that is controlled by relay 2
NC3, NO3, COM3: These pins link to a high-voltage device that is controlled by relay 3
NC4, NO4, COM4: These pins link to a high-voltage device that is controlled by relay 4

For information on connecting a relay to high-voltage, as well as the differences between a normally closed and a normally open relay, please refer to Arduino Nano - Relay tutorial.

It also has 4 jumpers, which can be used to choose between the low trigger and the high trigger for each relay.

Wiring Diagram

The 4-channel relay module requires a significant amount of energy, so it should NOT be powered directly from the 5V pin of the Arduino Nano. An external 5V power source must be used instead.

Therefore, we must use three power sources:

A 5V power adapter for the Arduino Nano
A 5V power adapter for the 4-channel relay module
A higher-voltage power adapter (12VDC, 24VDC, 48VDC, 220AC...) for items that are managed by the 4-channel relay module
A wiring diagram with the three power sources. The Arduino Nano can be powered either through a USB cable or a power jack, which is not shown in the image.

The wiring diagram between Arduino Nano and 4-channel relay module

This image is created using Fritzing. Click to enlarge image

We can lessen the amount of power adapters by utilizing a single 5V power source for both the Arduino Nano and the 4-channel relay module.

The wiring diagram between Arduino Nano and 4-channel relay module two power source

This image is created using Fritzing. Click to enlarge image

※ NOTE THAT:

If the four devices that are operated by a 4-channel relay module have the same voltage requirement, then we can use a single high-voltage power adapter to provide power to all of them. However, if the voltage requirements of these devices differ, then we will need to use different high-voltage power adapters for each device.

How To Program For 4-Channel Relay Module

Sets the Arduino Nano pin to digital output mode by utilizing the pinMode() function.

pinMode(PIN_RELAY_1, OUTPUT); pinMode(PIN_RELAY_2, OUTPUT); pinMode(PIN_RELAY_3, OUTPUT); pinMode(PIN_RELAY_4, OUTPUT);

Manage the relay's condition by utilizing the digitalWrite() function.

digitalWrite(PIN_RELAY_1, HIGH); digitalWrite(PIN_RELAY_2, HIGH); digitalWrite(PIN_RELAY_3, HIGH); digitalWrite(PIN_RELAY_4, HIGH);

Arduino Nano Code

/* * This Arduino Nano code was developed by newbiely.com * * This Arduino Nano code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano/arduino-nano-4-channel-relay-module */ #define PIN_RELAY_1 2 // The Arduino Nano pin connected to the IN1 pin of relay module #define PIN_RELAY_2 3 // The Arduino Nano pin connected to the IN2 pin of relay module #define PIN_RELAY_3 4 // The Arduino Nano pin connected to the IN3 pin of relay module #define PIN_RELAY_4 5 // The Arduino Nano pin connected to the IN4 pin of relay module // The setup function runs once on reset or power-up 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 repeats indefinitely 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); }

Detailed Instructions

Copy the code and open it with the Arduino IDE.
Click the Upload button on the Arduino IDE to compile and upload the code to the Arduino Nano.
Listen for the click sound of the relays.
Check the Serial Monitor for the result.

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

Function References

Learn More

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