one arduino to send data to another arduino via ethernet

I am hoping someone can help me with this. I have developed a pool control where i can access the pump, heat and light using the internet. I also have a temperature sensor using arduino as well. Currently the temp is sent to the control via rf communications but i don’t find this to be very reliable. I would like to instead, send the information (temp) over the network.

I have two sketches.

RECEIVER:

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

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {  
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(192, 168, 1, 177);

unsigned int localPort = 8888;      // local port to listen on

// An EthernetUDP instance to let us send and receive packets over UDP
EthernetUDP Udp;

char packetBuffer[UDP_TX_PACKET_MAX_SIZE]; //buffer to hold incoming packet,

void setup() {
  // start the Ethernet and UDP:
  Ethernet.begin(mac,ip);
  Udp.begin(localPort);

}

void loop() {

  int packetSize = Udp.parsePacket();
  if(packetSize)
  {
    Serial.print("Received packet of size ");
    Serial.println(packetSize);
    Serial.print("From ");
    IPAddress remote = Udp.remoteIP();
    for (int i =0; i < 4; i++)
    {
      Serial.print(remote[i], DEC);
      if (i < 3)
      {
        Serial.print(".");
      }
    }
    Serial.print(", port ");
    Serial.println(Udp.remotePort());

    // read the packet into packetBufffer
    Udp.read(packetBuffer,UDP_TX_PACKET_MAX_SIZE);
    Serial.println("Contents:");
    Serial.println(packetBuffer);
}
}

TRANSMITTER:

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

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {  
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(192, 168, 1, 177);

unsigned int localPort = 8888;      // local port to listen on

// An EthernetUDP instance to let us send and receive packets over UDP
EthernetUDP Udp;

void setup() {
  // start the Ethernet and UDP:
  Ethernet.begin(mac,ip);
  Udp.begin(localPort);

}

void loop() {

  Udp.beginPacket(Udp.remoteIP(), Udp.remotePort());
    Udp.write("hello");
    Udp.endPacket();

}

My question for starters is how does the sending unit know where to send the information. It specifies remoteIP and remotePort but shouldn’t this be declared in the set up?

Any help is appreciated.

My question for starters is how does the sending unit know where to send the information. It specifies remoteIP and remotePort but shouldn't this be declared in the set up?

Any help is appreciated.

Your sketches use UDP datagram. Something like my project here.

Ray

I'm not sure what that means.