Arduino Ethernet to Arduino Ethernet

Projects Networking, Protocols, and Devices
1

Hello

I want with my Arduino Uno to connect to a 2 Arduino UNO via Ethernet.
With a button on Ard. 1 can turn on, an LED to Ard. 2 .
When the LED on Ard. 2 Lights sends a message to Ard. 1

My question is who is the client and who is server.
Or maybe someone has a code example for me :slight_smile:

Thanks MFG ASRock :slight_smile:

2

My question is who is the client and who is server.

It doesn't really matter, as long as only one is a client and only one is a server.

The one that is the client can ask the server to do stuff, like turn pins on and off. The server can respond to the requests, but that is the only way the server can communicate with the client.

There is nothing Arduino-specific in your questions. Just general client/server architecture issues, which you don't seem to have a grasp of.

3

Thanks

but can i have 2 servers becose they must both send and receive ?

Mfg ASRock

4

Code that has both client and server functions.

//zoomkat 7-03-12, combined client and server
//simple button GET with iframe code
//for use with IDE 1.0
//open serial monitor and send an g to test client and
//see what the arduino client/server receives
//web page buttons make pins high/low
//use the ' in html instead of " to prevent having to escape the "
//address will look like http://192.168.1.102:84 when submited
//for use with W5100 based ethernet shields

#include <SPI.h>
#include <Ethernet.h>

byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //assign arduino mac address
byte ip[] = {192, 168, 1, 102 }; // ip in lan assigned to arduino
byte gateway[] = {192, 168, 1, 1 }; // internet access via router
byte subnet[] = {255, 255, 255, 0 }; //subnet mask
EthernetServer server(84); //server port arduino server will use
EthernetClient client;
char serverName[] = "web.comporium.net"; // (DNS) zoomkat's test web page server
//byte serverName[] = { 208, 104, 2, 86 }; // (IP) zoomkat web page server IP address

String readString; //used by server to capture GET request 

//////////////////////

void setup(){

  pinMode(5, OUTPUT); //pin selected to control
  pinMode(6, OUTPUT); //pin selected to control
  pinMode(7, OUTPUT); //pin selected to control
  pinMode(8, OUTPUT); //pin selected to control

  //pinMode(5, OUTPUT); //pin 5 selected to control
  Ethernet.begin(mac,ip,gateway,gateway,subnet); 
  server.begin();
  Serial.begin(9600); 
  Serial.println(F("server/client 1.0 test 7/03/12")); // keep track of what is loaded
  Serial.println(F("Send an g in serial monitor to test client")); // what to do to test client
}

void loop(){
  // check for serial input
  if (Serial.available() > 0) 
  {
    byte inChar;
    inChar = Serial.read();
    if(inChar == 'g')
    {
      sendGET(); // call client sendGET function
    }
  }  

  EthernetClient client = server.available();
  if (client) {
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();

        //read char by char HTTP request
        if (readString.length() < 100) {

          //store characters to string 
          readString += c; 
          //Serial.print(c);
        } 

        //if HTTP request has ended
        if (c == '\n') {

          ///////////////
          Serial.print(readString); //print to serial monitor for debuging 

            //now output HTML data header
          if(readString.indexOf('?') >=0) { //don't send new page
            client.println(F("HTTP/1.1 204 Zoomkat"));
            client.println();
            client.println();  
          }
          else {   
            client.println(F("HTTP/1.1 200 OK")); //send new page on browser request
            client.println(F("Content-Type: text/html"));
            client.println();

            client.println(F("<HTML>"));
            client.println(F("<HEAD>"));
            client.println(F("<TITLE>Arduino GET test page</TITLE>"));
            client.println(F("</HEAD>"));
            client.println(F("<BODY>"));

            client.println(F("<H1>Zoomkat's simple Arduino 1.0 button</H1>"));

            // DIY buttons
            client.println(F("Pin5"));
            client.println(F("<a href=/?on2 target=inlineframe>ON</a>")); 
            client.println(F("<a href=/?off3 target=inlineframe>OFF</a>

")); 

            client.println(F("Pin6"));
            client.println(F("<a href=/?on4 target=inlineframe>ON</a>")); 
            client.println(F("<a href=/?off5 target=inlineframe>OFF</a>

")); 

            client.println(F("Pin7"));
            client.println(F("<a href=/?on6 target=inlineframe>ON</a>")); 
            client.println(F("<a href=/?off7 target=inlineframe>OFF</a>

")); 

            client.println(F("Pin8"));
            client.println(F("<a href=/?on8 target=inlineframe>ON</a>")); 
            client.println(F("<a href=/?off9 target=inlineframe>OFF</a>

")); 

            client.println(F("Pins"));
            client.println(F("&nbsp;<a href=/?off2468 target=inlineframe>ALL ON</a>")); 
            client.println(F("&nbsp;<a href=/?off3579 target=inlineframe>ALL OFF</a>")); 

            client.println(F("<IFRAME name=inlineframe style='display:none'>"));          
            client.println(F("</IFRAME>"));

            client.println(F("</BODY>"));
            client.println(F("</HTML>"));
          }

          delay(1);
          //stopping client
          client.stop();

          ///////////////////// control arduino pin
          if(readString.indexOf('2') >0)//checks for 2
          {
            digitalWrite(5, HIGH);    // set pin 5 high
            Serial.println(F("Led 5 On"));
            Serial.println();
          }
          if(readString.indexOf('3') >0)//checks for 3
          {
            digitalWrite(5, LOW);    // set pin 5 low
            Serial.println(F("Led 5 Off"));
            Serial.println();
          }
          if(readString.indexOf('4') >0)//checks for 4
          {
            digitalWrite(6, HIGH);    // set pin 6 high
            Serial.println(F("Led 6 On"));
            Serial.println();
          }
          if(readString.indexOf('5') >0)//checks for 5
          {
            digitalWrite(6, LOW);    // set pin 6 low
            Serial.println(F("Led 6 Off"));
            Serial.println();
          }
          if(readString.indexOf('6') >0)//checks for 6
          {
            digitalWrite(7, HIGH);    // set pin 7 high
            Serial.println(F("Led 7 On"));
            Serial.println();
          }
          if(readString.indexOf('7') >0)//checks for 7
          {
            digitalWrite(7, LOW);    // set pin 7 low
            Serial.println(F("Led 7 Off"));
            Serial.println();
          }     
          if(readString.indexOf('8') >0)//checks for 8
          {
            digitalWrite(8, HIGH);    // set pin 8 high
            Serial.println(F("Led 8 On"));
            Serial.println();
          }
          if(readString.indexOf('9') >0)//checks for 9
          {
            digitalWrite(8, LOW);    // set pin 8 low
            Serial.println(F("Led 8 Off"));
            Serial.println();
          }         

          //clearing string for next read
          readString="";

        }
      }
    }
  }
} 

//////////////////////////
void sendGET() //client function to send and receive GET data from external server.
{
  if (client.connect(serverName, 80)) {
    Serial.println(F("connected"));
    client.println(F("GET /~shb/arduino.txt HTTP/1.1"));
    client.println(F("Host: web.comporium.net"));
    client.println(F("Connection: close"));
    client.println();
  } 
  else {
    Serial.println(F("connection failed"));
    Serial.println();
  }

  while(client.connected() && !client.available()) delay(1); //waits for data
  while (client.connected() || client.available()) { //connected or data available
    char c = client.read();
    Serial.print(c);
  }

  Serial.println();
  Serial.println(F("disconnecting."));
  Serial.println(F("=================="));
  Serial.println();
  client.stop();

}
5

Hello,
thanks for the Code.
But it isnt that what i want,because i havnt a WebPage.
I only send a "string" from one Ethernet Shield to an other Ethernet Shield.
If a Button on an Input (Ard.1) is pressed then Send a "message" to the (Ard.2) and an Output is HIGH. If the OUTPUT is HIGH then (Ard.2) sends a "message" to (Ard.1) and an OUTPUT is HIGH :slight_smile:

Thanks ASRock :slight_smile:

6

hey,

you can do multi direction as shown with the webserver you are requesting, the trick is in how you send and receive.

The way that I would set it up is one arduino unit as the server.
then I would have it post the following webpage when requested

client.println(F("clientname,pin1,pin2,pin3,etc"));

example: client.println(F("ar34,0,1,0,1,1"));

on the client arduino,
have it go read from the server and if it is clientnam is ar34 then parse the line to read in the data.

so the client can also send data to the server and having the server read and parse the information also. you don't need to use two servers because the client can always send data to the server and the server posts data for the client to read.

so if you have multiple clients then the server can post the info for all of them at the same time and the clients only parse the info that pertains to them.

hope that makes sense.

jasit

7

But it isnt that what i want,because i havnt a WebPage.

The posted code doesn't care weather the GET request it receives comes from a web browser or an arduino client. The code posted doesn't care weather it is sending a GET request to a web server like Apache or to an arduino running server code. The code is setup with a web page included so it can be tried using a single arduino.