UDP Communications

I have two Arduino UNOs with Ethernet shields and I am attempting to send a token from one to the other.

Both seem to initialize fine in setup.

But whenever I send a packet, I get an error occuring during the write function.

I’ve listed and attached both sketches. The “…console” sketch never sees a “packetsize” greater than zero.
I am sure it is something simple, but I’ve spent weeks debugging this problem…

Any ideas?

// sends a message first

#include <SPI.h>
#include <Ethernet.h>
// #include <EthernetUdp2.h>

#define localID 10 // local
#define remoteID 20 // remote
#define localPORT 8888 // Port
#define EthMegPin 53
#define debugDelay 2500
#define Halt while(true)
#define Forever while(true)
#define aWait 2000

// define UDP object
EthernetUDP sendUdp;

char UDPRecvBuffer[UDP_TX_PACKET_MAX_SIZE];
char UDPSendBuffer = “ack”;
byte mac = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, localID };

IPAddress local_IP(10, 1, 1, localID);
IPAddress remote_IP(10, 1, 1, remoteID);
int packetSize;
byte localScriptToken = 0;
int remote_message = 100;

void setup() {
Serial.begin(9600);

pinMode(EthMegPin, OUTPUT);
digitalWrite(EthMegPin, HIGH);
// Ethernet.init(10); // Most Arduino shields

// localID read in setup
// mac[5] = localID;
// local_IP[3] = localID;
// remote_IP[3] = remoteID;
for (int i = 0; i < 4; i++) {
Serial.print(local_IP*);*

  • if (i < 3) Serial.print(", ");*
  • }; Serial.println(" <-local");*
  • IPAddress remote_IP(10, 1, 1, remoteID);*
  • for (int i = 0; i < 4; i++) {*
    Serial.print(remote_IP*);
    _
    if (i < 3) Serial.print(", “);_
    _
    }; Serial.println(” <-remote");_
    _
    Serial.println();_
    Ethernet.begin(mac, local_IP);
    _
    // Check for Ethernet hardware present*_
    * if (Ethernet.hardwareStatus() == EthernetNoHardware) {*
    * Serial.println(“Setup: Ethernet shield was not found. Sorry, can’t run without hardware. :(”);*
    * Halt;*
    * } else {*
    * Serial.println(“Setup: Found Ethernet Shield”);*
    * }*
    * if (Ethernet.linkStatus() == LinkOFF) {*
    * Serial.println(“Setup: Ethernet cable is not connected.”);*
    * Halt;*
    * } else {*
    * Serial.println(“Setup: Cable connected”);*
    * }*
    * int Udp_Conn = sendUdp.begin(localPORT);
    if (Udp_Conn) {
    _
    Serial.print(“Setup: UDP port connection successful to “);_
    _
    Serial.println(localPORT);_
    _
    }_
    _
    else {_
    _
    Serial.print(“Setup: UDP port connection failed to “);_
    _
    Serial.println(localPORT);_
    _
    Halt;_
    _
    }_
    _
    Serial.println();_
    _
    }_
    void loop() {
    // int UdpConn = sendUdp.beginPacket(remote_IP, sendUdp.remotePort());
    int UdpConn = sendUdp.beginPacket(remote_IP, localPORT);
    _
    for (int i = 0; i < 4; i++) {_
    Serial.print(remote_IP);
    _ if (i < 3) Serial.print(”, “);
    }; Serial.print(”:”);
    Serial.print(localPORT);
    Serial.println(”: <-remote”);
    if (UdpConn) {
    Serial.println(“Loop: Begin packet successful”);
    }
    else {_
    Serial.println(“Loop: UDP packet begin failed. Host not found");*
    * for (int i = 0; i < 4; i++) {_
    Serial.print(local_IP);
    _ if (i < 3) Serial.print(”, “);
    }; Serial.println(” <-local");
    for (int i = 0; i < 4; i++) {_

    Serial.print(remote_IP);
    _ if (i < 3) Serial.print(", “);
    }; Serial.println(” <-remote");
    }_

    remote_message ++;
    itoa(remote_message, UDPSendBuffer, 10);
    _ int charsSent = sendUdp.write(UDPSendBuffer);
    // delay(debugDelay);
    delay(100);
    Serial.print(charsSent);
    Serial.println(" characters sent");
    int UdpSent = sendUdp.endPacket();
    if (UdpSent) {
    Serial.println(“Loop: Message sent via UDP”);
    }
    else {
    Serial.print(“Loop: Error occurred during write [”);
    Serial.print(UdpSent);
    Serial.println("]");
    }
    delay(aWait);
    Halt;
    }[/quote]
    Something went wrong.
    Trying to correct listing
    of Receive sketch. The
    attachment is good.
    Until then…_

    TII-Interact_commsTest_Send.ino (3.3 KB)
    TII-Interact_commsTest_Console.ino (2.61 KB)*

I've listed and attached both sketches.

Yes, but incorrectly... Please read these two posts:

General Guidance and How to use the Forum
and
Read this before posting a programming question ...

I’m already familiar with those posts, having posted successfully several previous posts.

Something happened with the second listing. It was completely destroyed. I’ve since removed it, depending on my attachments.

I don’t know what happened to my original posts. Since I don’t haveaccesd to the platform on which my source resides, it will take a while for me to correct the post itself. Please in the interim look at my attachments.