Basic Arduino relay shield example

The Relay Shield features four high quality relays and provides NO/NC interfaces, four dynamic LED indicators to show the on/off state of each relay, and the standardized shield form factor to provide a smooth connection to Arduino compatible boards.

Product details

Relay Shield v0.9b 5V 4-Channel Relay Module for Arduino – (Works with official Arduino Boards) – $9.73   Features Relay Shield is a small current signal control module can achieve single chip to control large power device Widely use in singlechip home device Can be plug to the main board which is compatible with Arduino; 4-channel relay stand Arduino Shield interface; 3-M3 screw hole easy to install Driven by 5V / 3.3V normally open contact close; With red LED indicator onboard Note: Please avoid the green terminal short-circuit by the housing as connecting with Arduino UNO main board Specification Power voltage: 4.75~5V; Power consumption (at 5V): 180mA; Opening and closing time per minute: 30 times; Every channel maximum convert voltage: AC 125V / DC 24V; Every channel maximum converts current: 3A Application High performance expansion board;

In this example we will show how to use one of the relays on the shield to control an LED by switching it on and off.

Here is a picture of the relay shield

relay shield

J1 Interface/Terminal Pin Description:

COM1 (Common Pin) : The relay pin controlled from the digital pin.
NC1 (Normally Closed): This terminal will be connected to COM1 when the RELAY1 control pin (Digital 7 I/O pin) is set low and disconnected when the RELAY1 control pin is set high.
NO1 (Normally Open): This terminal will be connected to COM1 when the RELAY1 control pin (Digital 7 I/O pin) is set high and disconnected when the RELAY1 control pin is set low.

Schematic

Here is a simple picture showing how to connect the LED to the relay shield

relay shield and LED

Code

No libraries required here

[codesyntax lang=”cpp”]

int RelayControl1 = 7;    // Digital Arduino Pin used to control the motor
 

void setup()  
{
    pinMode(RelayControl1, OUTPUT);
}
 

void loop()  
{
    digitalWrite(RelayControl1,HIGH);// NO1 and COM1 Connected (LED on)
    delay(1000); // wait 1000 milliseconds (1 second)
    digitalWrite(RelayControl1,LOW);// NO1 and COM1 Disconnected (LED off)
    delay(1000); // wait 1000 milliseconds (1 second)
}

[/codesyntax]

Links

Four Channel Relay Electronic 5V 4 Channel Relay Shield Module For Arduino