merci à tous pour votre aide.
Je vous donne mon code utilié, si vous voyez un truc 
Merci
// ******************* START librairies *******************
#include <SPI.h>
#include <Ethernet2.h>
#define DEBUG 1 ; //Debug activation ON = 1 ; OFF = 0
// ******************* END librairies *******************
// ******************* START VAR *******************
char DataRead[50];
char DataSize[4];
//char Data[4];
int i,j,m;
// ******************* END VAR *******************
// ******************* START Ethernet *******************
char server[] = "www.domaine.fr"; // name address for Google (using DNS)
// Set the static IP address to use if the DHCP fails to assign
byte mac[] = { 0x90, 0xA2, 0xDA, 0x11, 0x23, 0xA6 }; // Mac address 99-B8-DC-A0-72-F2
IPAddress dnServer(8, 8, 8, 8);
IPAddress gateway(192, 168, 2, 1);
IPAddress subnet(255, 255, 255, 0);
IPAddress ip(192, 168, 2, 195);
EthernetClient client; // Type mode between Server and Client
// ******************* END Ethernet *******************
// ******************* START Setup *******************
void setup() {
// Start Serial cable
Serial.begin(9600); // Open serial communications and wait for port to open:
while (!Serial) {;} // wait for serial port to connect. Needed for Leonardo only
// Mode Relais
pinMode(4, OUTPUT);
digitalWrite(4, LOW);
// Start Ethernet
if (Ethernet.begin(mac) == 0) { // start the Ethernet connection:
Serial.println("Failed to configure Ethernet using DHCP"); // no point in carrying on, so do nothing forevermore:
//Ethernet.begin(mac, ip); // try to congifure using IP address instead of DHCP:
Ethernet.begin(mac, ip, dnServer, gateway, subnet);
}
#ifdef DEBUG
Serial.print("My IP address: ");
Serial.println(Ethernet.localIP());
#endif
}
// ******************* END Setup *******************
// ******************* START loop *******************
void loop()
{
//*************************** END Read g.php Ethernet Data ***************************
#ifdef DEBUG
Serial.println("connecting to g.php...");
#endif
client.stop();
if (client.connect(server, 80)) {
#ifdef DEBUG
Serial.println("connected");
#endif
client.print("GET /g.php");
client.println(" HTTP/1.1");
client.println("HOST: www.domaine.fr");
client.println("User-Agent: arduino-ethernet");
client.println("Connection: close");
client.println();
j=0;
i=0;
m=0;
delay(500);
// if there are incoming bytes available
// from the server, read them and print them:
while(client.available()) {
//Serial.print(client.read());
//char c = client.read();
//Serial.print(c);
if (client.read() == '\n') {
if (client.read() == '\r')
{
client.read();
//Serial.println("DataSize : ");
while(client.available()) {
char c = client.read();
if(c=='\r')
break;
DataSize[j]=c;
j++;
//Serial.print(c);
}
client.read();
//Serial.println("Data : ");
while(client.available()) {
char c = client.read();
if(c=='\r'){
break;
DataRead[i]='\0';}
DataRead[i]=c;
i++;
//Serial.print(c);
}
}
}
if(j==1)
break;
}
// if the server's disconnected, stop the client:
if (!client.connected()) {
#ifdef DEBUG
Serial.println("Disconnecting to g.php.");
#endif
client.stop();}
//*************************** start Send XBee Data ***************************
uint32_t msdw, lsdw;
char CharAddr64[17];
char Data[2];
memcpy( CharAddr64, DataRead, 16 );
CharAddr64[16] = '\0';
uint8_t len = strlen(CharAddr64);
memcpy( Data, &DataRead[len+1], 16 );
Data[2] = '\0';
int pos = atoi(Data);
lsdw = strtoul(&DataRead[len-8], NULL, 16);
DataRead[len-8] = '\0';
msdw = strtoul(DataRead, NULL, 16);
#ifdef DEBUG
Serial.println("*******************");
Serial.print("DataRead: ");
for (i = 0; i < sizeof(DataRead); i++) {
Serial.print(DataRead[i]);
}
Serial.println("");
//*************************** START DATA traitement ***************************
Serial.print("Adresse char : ");
Serial.println(CharAddr64);
Serial.print("len : ");
Serial.println(len);
Serial.print("len-8 : ");
Serial.println(Data);
Serial.print("pos : ");
Serial.println(pos);
Serial.print("Adresse : ");
Serial.print(msdw, HEX);
Serial.print(" - ");
Serial.print(lsdw, HEX);
Serial.println("");
#endif
switch (pos) {
case 01:
Serial.println("OFF");
digitalWrite(4, LOW);
break;
case 11:
Serial.println("ON");
digitalWrite(4, HIGH);
break;
}
}
else {
// kf you didn't get a connection to the server:
#ifdef DEBUG
Serial.println("connection failed");
#endif
}
//*************************** END Read g.php Ethernet Data ***************************
}