//D10 -> RELAY4

void setup(){

for(int i = 0; i < 4; i++)

pinMode(relayPin[i],OUTPUT);

}

// an sample to switch the 4 relays

void loop(){

int i;

for(i = 0; i < 4; i++)

digitalWrite(relayPin[i],HIGH);

delay(1000);

for(i = 0; i < 4; i++)

digitalWrite(relayPin[i],LOW);

delay(1000);

}

A more elaborate sample code

/*

# This Sample code is for testing the Relay shield V2.1 for Arduino.

# Editor : Phoebe

# Date

: 2013.2.28

# Ver

: 0.1

# Product: Relay shield for Arduino

# SKU

: DRI0144

# Hardwares:

1. Arduino UNO

2. Relay Shield For Arduino V2.1

3

Power Supply:7~ 12V

*/