ntp server code : no output on serial monitor

hello all

can someone pls help me about my code ? it is edited example of udp ntp client and when i run it, serial monitor displays nothing … my arduino hardware is arduino uno with ethernet shield on it and in it is connected ethernet cable. i need static ip as is defined in code and i have uploaded Ethernet to 2.0.0 from github which works. do someone help me ? sory my english :slight_smile:

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

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield

byte mac[] = {0xDE,0xAD,0xBE,0xEF,0xFE,0xED};
IPAddress ip(192,168,243,253);
IPAddress gateway(192,168,240,2);  
IPAddress subnet(255, 255, 252, 0);
IPAddress dns (192,168,240,55);

unsigned int localPort = 8888;       // local port to listen for UDP packets

const char timeServer[] = "time.nist.gov"; // time.nist.gov NTP server

const int NTP_PACKET_SIZE = 48; // NTP time stamp is in the first 48 bytes of the message

byte packetBuffer[NTP_PACKET_SIZE]; //buffer to hold incoming and outgoing packets

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

void setup() {
  // You can use Ethernet.init(pin) to configure the CS pin
  //Ethernet.init(10);  // Most Arduino shields
  //Ethernet.init(5);   // MKR ETH shield
  //Ethernet.init(0);   // Teensy 2.0
  //Ethernet.init(20);  // Teensy++ 2.0
  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet

  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  Ethernet.begin(mac, ip, dns, gateway, subnet);


  // start Ethernet and UDP
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // Check for Ethernet hardware present
    if (Ethernet.hardwareStatus() == EthernetNoHardware) {
      Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    } else if (Ethernet.linkStatus() == LinkOFF) {
      Serial.println("Ethernet cable is not connected.");
    }
    // no point in carrying on, so do nothing forevermore:
    while (true) {
      delay(1);
    }
  }
  Udp.begin(localPort);
}

void loop() {
  sendNTPpacket(timeServer); // send an NTP packet to a time server

  // wait to see if a reply is available
  delay(1000);
  if (Udp.parsePacket()) {
    // We've received a packet, read the data from it
    Udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer

    // the timestamp starts at byte 40 of the received packet and is four bytes,
    // or two words, long. First, extract the two words:

    unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
    unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
    // combine the four bytes (two words) into a long integer
    // this is NTP time (seconds since Jan 1 1900):
    unsigned long secsSince1900 = highWord << 16 | lowWord;
    Serial.print("Seconds since Jan 1 1900 = ");
    Serial.println(secsSince1900);

    // now convert NTP time into everyday time:
    Serial.print("Unix time = ");
    // Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
    const unsigned long seventyYears = 2208988800UL;
    // subtract seventy years:
    unsigned long epoch = secsSince1900 - seventyYears;
    // print Unix time:
    Serial.println(epoch);


    // print the hour, minute and second:
    Serial.print("The UTC time is ");       // UTC is the time at Greenwich Meridian (GMT)
    Serial.print((epoch  % 86400L) / 3600); // print the hour (86400 equals secs per day)
    Serial.print(':');
    if (((epoch % 3600) / 60) < 10) {
      // In the first 10 minutes of each hour, we'll want a leading '0'
      Serial.print('0');
    }
    Serial.print((epoch  % 3600) / 60); // print the minute (3600 equals secs per minute)
    Serial.print(':');
    if ((epoch % 60) < 10) {
      // In the first 10 seconds of each minute, we'll want a leading '0'
      Serial.print('0');
    }
    Serial.println(epoch % 60); // print the second
  }
  // wait ten seconds before asking for the time again
  delay(10000);
  Ethernet.maintain();
}

// send an NTP request to the time server at the given address
void sendNTPpacket(const char * address) {
  // set all bytes in the buffer to 0
  memset(packetBuffer, 0, NTP_PACKET_SIZE);
  // Initialize values needed to form NTP request
  // (see URL above for details on the packets)
  packetBuffer[0] = 0b11100011;   // LI, Version, Mode
  packetBuffer[1] = 0;     // Stratum, or type of clock
  packetBuffer[2] = 6;     // Polling Interval
  packetBuffer[3] = 0xEC;  // Peer Clock Precision
  // 8 bytes of zero for Root Delay & Root Dispersion
  packetBuffer[12]  = 49;
  packetBuffer[13]  = 0x4E;
  packetBuffer[14]  = 49;
  packetBuffer[15]  = 52;

  // all NTP fields have been given values, now
  // you can send a packet requesting a timestamp:
  Udp.beginPacket(address, 123); // NTP requests are to port 123
  Udp.write(packetBuffer, NTP_PACKET_SIZE);
  Udp.endPacket();
}

That probably means you didn't get a response back. There might be numerous reasons for this, my guess is that a firewall on the router is blocking the requests. But that's a wild guess as you didn't tell us anything about how you set up your network.

I don't think so, because first of all in code is written this :

void setup() {

  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // Check for Ethernet hardware present
    if (Ethernet.hardwareStatus() == EthernetNoHardware) {
      Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    } else if (Ethernet.linkStatus() == LinkOFF) {
      Serial.println("Ethernet cable is not connected.");
    }
    // no point in carrying on, so do nothing forevermore:
    while (true) {
      delay(1);
    }
  }
}

doesn't this condition had to write something first on the serial monitor ? it is in setup so just once, but it doesn't write even this ...

UPDATE:
I've tried to debug it and it is as you said ... arduino sends packet, but there is no response back ... and i think problem could be on this line :

  packetBuffer[0] = 0b11100011;   // LI, Version, Mode

that 0b11100011 is highlighted in arduino API ... do you think it is wrong ?

that 0b11100011 is highlighted in arduino API ... do you think it is wrong ?

It's not highlighted in my IDE. Does it tell you an error? Do you have an outdated version of the IDE?