With Data becoming a major Asset in the Internet generation, it has been stored at locations called Data Centers. Managing the equipments which hold the Data is simple as they are accessible over the Internet. If you are aware of how electronic peripherals work esp. related to computers, you will know that every once in a while they malfunction and need to be rebooted. The problem is that in most cases these devices don’t respond so rebooting them in a conventional way is not possible. The only way to restart them would be power cycling the device. This would not be much problem if you have a manned Data Center or you have remote hands and eyes support. The problem is when you have a malfunctioning equipment at a place where there is no one to look after it. At such times, an IP PDU (Internet Protocol Power Distribution Unit) can be very helpful. This is a Power Strip which you can control over the Internet to power cycle devices plugged into it. In this article, we will look into how to use an Arduino YUN to make an IP PDU aka IP Power strip aka IP Power extension. The reason I am making this is because with Arduino YUN “I have got the Power”.

Note: This project involves mains electricity and all precautions must be taken while dealing with it. The base of the Relay as well as the screws on the relay terminal carry AC voltage.

Requirements

1) Power Strip (preferably with buttons)

 

2) Arduino Yun

3) 4 Channel 5V Relay Module

4) Junction Box

The Setup

The base of the project is to insert our own switching system instead of utilizing the buttons of the power strip for switching. The Neutral and Earth will go intact to the power strip. We will have to break the live going to the strip and put our switching system in between. The Live will go to Common Terminal of the Relay. You can put the Live in any of the common terminal and take wires from that terminal to other 3 common terminals. There are 2 ways you can take live from the relay to the strip depending on the situation you want to use in. If you want to use the strip at a place where power to a device is critical eg. a Server then you must take Live from Normally Closed terminal. What this means is that even if anything happens to the Arduino or if the Arduino Powers Off, the NC (normally closed) will still supply power to the appliance connected. If you are using the strip for home appliances then you don’t want continuous power to the appliance if the Arduino fails. For this you will have to take Live from the Normally Opened (NO) terminal. This means that when you send a signal for the strip port to be ON, only then it will turn ON. In this project, I am connecting it to NO as I want to use it at home.

In order to control the relay, the relay board has to be provided with 5V from the Arduino 5V. The GND will be connected to Arduino GND. Pins 3, 4, 5 and 6 of YUN will be connected to CH1, CH2, CH3 and CH4 respectively on the relay board. Signals on these pins will decide the state of the relay.

Setting up Arduino Yun

In order for the Yun to have Internet connectivity, it has to be hooked to our Home Internet using either Wifi or Ethernet. I have connected the Yun to the Home Wifi network. After this, the Yun should have Internet connectivity. It is time now to upload the sketch to the Yun. When the sketch is uploaded, the web page present in the sketch www directory will also be moved to the Yun. The web page can be accessed as http://ip-address-of-Yun/sd/ip_pdu. The sketch as well as the HTML page can be found at the end of the tutorial. Also, the explanation for it can be found on my blog here. This page will not be accessible over the Internet without much hard work. You will have to do port forwarding on your router, you will have to setup Dynamic DNS, etc. The better way to make the Yun web page accessible over the Internet is via Yaler service. You can access the procedure here. After this, the page should be accessible as http://gsiot-xxxx-xxxx.try.yaler.net/sd/ip_pdu

Sketch and HTML Upload procedure

If you have an sd card in the Yun and an /arduino/www created in the root directory of the sd card, the Yun will automatically transfer the HTML you wrote from your sketch directory to /arduino/www/sketch folder. For example, if my sketch is in \Documents\Arduino\”sketch” folder, I will have to create a folder www in “sketch” directory and have my HTML as index.html. Now when I upload the sketch using wifi, the index.html will be placed in /arduino/www/”sketch”/index.html in the Yun and you can access this page by entering “http://ip address of yun/sd/sketch”. Following is an example video explaining the above procedure

Demo of Switching On and Off of Power Strip over the Internet

Video Tutorial for accessing Arduino YUN over the Internet

Files

You can find the INO file, HTML file and buttons here

HTML Code

<html>
<head>
<title>Arduino Yun I/O shield</title>

window.onload=statusPin;
function statusPin(){
morestatus();
}
function morestatus(){
setTimeout(morestatus, 2000);
document.getElementById(“description”).innerHTML = “— wait … —“;
server = “/arduino/status/99”;
request = new XMLHttpRequest();
request.onreadystatechange = updateasyncstatus;
request.open(“GET”, server, true);
request.send(null);
}
function updateasyncstatus(){
if ((request.readyState == 4) && (request.status == 200))
{
result = request.responseText;
document.getElementById(“description”).innerHTML = result;
fullset = result.split(“#”);
document.getElementById(“description”).innerHTML = fullset;
for(i = 1; i
</head>
<font face=”Arial”>
<table name=”Title” border=”1″ style=”width: 256px;” cellpadding=”6″>
<tr> <th align=”center” colspan=”4″ >Arduino IP PDU</th></tr>
</table>
<table name=”Table” border=”1″ cellpadding=”6″>
<tr> <th align=”center” colspan=”4″ >Power Control</th></tr>
<tr>
<td align=”center”>
1
<br>
<input type=”hidden” name=”pin” value=”3″ id=”pin3″ />
<input type=”hidden” name=”action” value=”0″ id=”action3″ />
<img src=”off.jpg” width=”50″ id=”image3″ onclick=”sendrelay(document.getElementById(‘pin3’).value,document.getElementById(‘action3’).value);”/>
</td>
<td align=”center”>
2
<br>
<input type=”hidden” name=”pin” value=”4″ id=”pin4″ />
<input type=”hidden” name=”action” value=”0″ id=”action4″ />
<img src=”off.jpg” width=”50″ id=”image4″ onclick=”sendrelay(document.getElementById(‘pin4’).value,document.getElementById(‘action4’).value);”/>
</td>
<td align=”center”>
3
<br>
<input type=”hidden” name=”pin” value=”5″ id=”pin5″ />
<input type=”hidden” name=”action” value=”0″ id=”action5″ />
<img src=”off.jpg” width=”50″ id=”image5″ onclick=”sendrelay(document.getElementById(‘pin5’).value,
document.getElementById(‘action5’).value);”/>
</td>
<td align=”center”>
4
<br>
<input type=”hidden” name=”pin” value=”6″ id=”pin6″ />
<input type=”hidden” name=”action” value=”0″ id=”action6″ />
<img src=”off.jpg” width=”50″ id=”image6″ onclick=”sendrelay(document.getElementById(‘pin6’).value,
document.getElementById(‘action6’).value);”/>
</td>
</tr>
</table>
<br><br>
<br><br>
<p id=”description”> – </p>
</font>
</html>

Arduino Yun Sketch

#include <Bridge.h>
#include <YunServer.h>
#include <YunClient.h>
int DigitalPin[] = { 3, 4, 5, 6};
YunServer server;
void setup() {
pinMode(3,OUTPUT);
pinMode(4,OUTPUT);
pinMode(5,OUTPUT);
pinMode(6,OUTPUT);
digitalWrite(13, LOW);
Bridge.begin();
digitalWrite(13, HIGH);
server.listenOnLocalhost();
server.begin();
}
void loop() {
YunClient client = server.accept();
if (client) {
process(client);
client.stop();
}
delay(50);
}
void process(YunClient client) {
String command = client.readStringUntil(‘/’);
if (command == “digital”) {
digitalCommand(client);
}
if (command == “status”) {
statusCommand(client);
}
}
void digitalCommand(YunClient client) {
int pin, value;
pin = client.parseInt();
if (client.read() == ‘/’) {
value = client.parseInt();
digitalWrite(pin, value);
}
else {
value = digitalRead(pin);
}
client.print(F(“digital,”));
client.print(pin);
client.print(F(“,”));
client.println(value);
}
void statusCommand(YunClient client) {
int pin, value;
client.print(F(“status”));
for (int thisPin = 0; thisPin < 4; thisPin++) {
pin = DigitalPin[thisPin];
value = digitalRead(pin);
client.print(F(“#”));
client.print(pin);
client.print(F(“=”));
client.print(value);
}
client.println(“”);
}