Working with the SainSmart 5v Relay Board

There is a 6 pin male header, so you will need a cable or female pins to slide over the header to connect it to your Arduino. Pin 1 connects to Arduino GND, Pins 2-5 to Digital output pins, and Pin 6 to Arduino 5v. A red LED for each relay lights when active (LOW).

int relayPin1 = 7;                 // IN1 connected to digital pin 7
int relayPin2 = 8;                 // IN2 connected to digital pin 8
int relayPin3 = 9;                 // IN3 connected to digital pin 9
int relayPin4 = 10;                // IN4 connected to digital pin 10

void setup()
{
pinMode(relayPin1, OUTPUT);      // sets the digital pin as output
pinMode(relayPin2, OUTPUT);      // sets the digital pin as output
pinMode(relayPin3, OUTPUT);      // sets the digital pin as output
pinMode(relayPin4, OUTPUT);      // sets the digital pin as output
digitalWrite(relayPin1, HIGH);        // Prevents relays from starting up engaged
digitalWrite(relayPin2, HIGH);        // Prevents relays from starting up engaged
digitalWrite(relayPin3, HIGH);        // Prevents relays from starting up engaged
digitalWrite(relayPin4, HIGH);        // Prevents relays from starting up engaged
}

void loop()
{
digitalWrite(relayPin1, LOW);   // energizes the relay and lights the LED
digitalWrite(relayPin2, LOW);   // energizes the relay and lights the LED
digitalWrite(relayPin3, LOW);   // energizes the relay and lights the LED
digitalWrite(relayPin4, LOW);   // energizes the relay and lights the LED
delay(1000);                  // waits for a second
digitalWrite(relayPin1, HIGH);    // de-energizes the relay and LED is off
digitalWrite(relayPin2, HIGH);    // de-energizes the relay and LED is off
digitalWrite(relayPin3, HIGH);    // de-energizes the relay and LED is off
digitalWrite(relayPin4, HIGH);    // de-energizes the relay and LED is off
delay(1000);                  // waits for a second
}

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