Ks0251 keyestudio 4-channel Relay Shield

From Keyestudio Wiki
Jump to: navigation, search
Keyestudio 4-channel Relay Shield


The keyestudio relay shield has integrated a 4-channel 5V relay module, which is fully compatible with UNO R3 control board. The 4-channel relay on the shield is active at HIGH level. Separately connect the 4-channel relay to the digital port 4, 5, 6, 7 on the UNO R3 board, then through controlling output HIGH or LOW to control the relay on and off.


  • The relay shield is 5V active HIGH
  • Contact capacity: AC120V / 3A ; DC24V/3A
  • Onboard LED indicator for relay output status
  • Indicator: 4 LEDs are red when the relay is driven high, the corresponding indicator will light up.
  • Standard interface can be directly connected with microcontrollers.
  • Fully compatible with UNO R3 board
  • Be able to control various appliances and other equipment with large current.
  • 3 M3 screw positioning holes for easy installation
  • Power Interface: 5V DC power interface
  • Channel: 4 channel
  • PCB Color: Black


  • Size: 69mm*54mm*26mm
  • Weight: 39.4g

Ks0251 dimensions.png


Ks0251 pinouts.jpg
Relay Terminals:

  • Terminal high-power, high-current high voltage can be connected to the device.
  • When D4 is High, RELAY 4 turns on, LED4 lights up, COM4 and NO4 connected, COM4 and NC4 disconnected. If D4 is LOW, RELAY 4 turns off, LED4 not light, COM4 and NO4 disconnected, COM4 and NC4 connected.
  • When D5 is High, RELAY 3 turns on, LED3 lights up, COM3 and NO3 connected, COM3 and NC3 disconnected. If D5 is LOW, RELAY 3 turns off, LED3 not light, COM3 and NO3 disconnected, COM3 and NC3 connected.
  • When D6 is High, RELAY 2 turns on, LED2 lights up, COM2 and NO2 connected, COM2 and NC2 disconnected. If D6 is LOW, RELAY 2 turns off, LED2 not light, COM2 and NO2 disconnected, COM2 and NC2 connected.
  • When D7 is High, RELAY 1 turns on, LED1 lights up, COM1 and NO1 connected, COM1 and NC1 disconnected. If D7 is LOW, RELAY 1 turns off, LED1 not light, COM1 and NO1 disconnected, COM1 and NC1 connected.

Hookup Guide

Simply stack the shield on the UNO board .
Ks0251 Connect.png

Sample Code

int BASE = 4 ;  //The first relay is connected to the I / O port
int NUM = 4;   //Total number of relays

void setup()
   for (int i = BASE; i < BASE + NUM; i ++) 
     pinMode(i, OUTPUT);   //Set the number I/O port to outputs

void loop()
   for (int i = BASE; i < BASE + NUM; i ++) 
     digitalWrite(i, LOW);    //Set the number I/O port outputs to "low", that is, gradually turn off the relay.
     delay(200);        //delay 0.2S
   for (int i = BASE; i < BASE + NUM; i ++) 
     digitalWrite(i, HIGH);    //Set the number I/O port outputs to "high", that is, gradually turn on relay.
     delay(200);        //delay 0.2S

Ks0251 upload.png

Test Result

Done uploading the above code, you should see the 4-channel relay is first connected, and then disconnected one after another, repeatedly.
Ks0251 Result.png


Download the PDF file here:

Download the code:


Get One Now