I am using a fairly simple code using Arduino UNO and Ethernet Shield W5100. The task is to connect the shield with the server and if it gets connected read the reading from the sensor (Rotary Encoder in my case), but after a few seconds approximately 20~30 sec the client gets disconnected. My Code is below, so Help is requested.

My Code

#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //Setting MAC Address

IPAddress server(192,168,8,118); //Setting IP Address of the Server i.e this machine
IPAddress ip(192,168,8,117); // Setting IP address of the LAN Card 

EthernetClient client; //Setting the Client Object

// Arduino Pin defiinations
#define encoder0PinA 2 
#define encoder0PinB 3
#define encoder0Btn 4
//Global Variable definations
int encoder0Pos = 0;
const float pi = 3.14;
const float R = 3.25;
const int N = 40;
float distance = 0;

//Setting up One Time Procedures
void setup() {
  Ethernet.begin(mac, ip);
  pinMode(encoder0PinA, INPUT_PULLUP);
  pinMode(encoder0PinB, INPUT_PULLUP);
  pinMode(encoder0Btn, INPUT_PULLUP);

  //Setting up Server Conection with Arduino Ehternet Shield
  if (client.connect(server,8888)) {
      Serial.println("Not connected");
   attachInterrupt(0, doEncoder, CHANGE);

void loop() {

void doEncoder()
  if (client.connected()) 

    if (digitalRead(encoder0PinA) == digitalRead(encoder0PinB))
  /* The rotary encoder measures the number of the rotation but we have to convert the rotation into travelled distance. 
   * Travelled distance depends on the diameter of the wheel. Rotary encoder moves 40 steps in one complete rotation (360 degree). 
   * Steps per rotation depends on the rotary encoder which can be changed from 8 to 48, but in our case it is 40. 
   * Suppose N is the steps per rotation and R is the radius of wheel. therefore,
   * Travelled distance in one Rotation is = 2xπxR
   * Travelled distance in one Step is     = 2xπxR/N
  distance = ((2*pi*R)/N) * encoder0Pos;
  Serial.print( distance);
  Serial.println("cm  ");
      Serial.println("Client Disconnected...");


  • don't do Ethernet in interrupt
    – Juraj
    May 11 at 13:57
  • move your ISR code into loop() ... only update encoder0Pos and set a flag inside ISR ... run code inside loop() if flag is set, and then clear the flag
    – jsotola
    May 11 at 13:58
  • 1
    By any chance, are you using a MicroSoft Operating System to determine if the Arduino Ethernet Shield is on or off line? Things may have improved (or not), but I once wasted hours because the MicroSoft OS decided the network device I was testing was bad and disabled the network it and the device it was connected to with out saying much of anything. Since then I have always tried to use Linux Operating Systems when testing Ethernet devices.
    – st2000
    May 11 at 13:59
  • 1
    I would recommend to use the Encoder library, read it in loop() and send the value if it changed
    – Juraj
    May 11 at 14:13


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.