Profinet DCP interaction based on experimental protocol implementation for Apache PLC4X.

Main.java

import org.apache.plc4x.java.PlcDriverManager;
import org.apache.plc4x.java.api.PlcConnection;
import org.apache.plc4x.java.api.messages.PlcSubscriptionEvent;
import org.apache.plc4x.java.utils.rawsockets.netty.RawSocketChannel;

import java.util.concurrent.TimeUnit;
import java.util.function.Consumer;

// Very simple example showing how to request profinet-dcp identification.
// Answers in line 23 are returned as PlcStruct (which is a map), for example:
// {"station.type": "SIMATIC-PC","station.name": "desktop-om18vq9","device.id": 514,"device.role": 0,"ip.address": "10.10.10.139","ip.mask": "255.255.255.0","ip.gateway": "10.10.10.1"}
public class Main {

    public static void main(String[] args) throws Exception {
        PlcConnection connection = new PlcDriverManager().getConnection("profinet-dcp:raw://eno0?sender=<my-ma-address>");
        connection.connect();

        // nodes which do answer will trigger subscription event with "nodeDiscovery" field containing device description
        connection.subscriptionRequestBuilder().addEventField("nodeDiscovery", "IDENTIFY_RESPONSE:").build().execute().whenComplete((r, e) -> {
            r.getSubscriptionHandle("nodeDiscovery").register(new Consumer<PlcSubscriptionEvent>() {
                @Override
                public void accept(PlcSubscriptionEvent plcSubscriptionEvent) {
                    System.out.println("Received subscription event " + plcSubscriptionEvent.getFieldNames() + "\n  " +
                        "status: " + plcSubscriptionEvent.getResponseCode("nodeDiscovery") + "\n  " +
                        "details: " + plcSubscriptionEvent.getPlcValue("nodeDiscovery") + "\n  " +
                        "time: " + plcSubscriptionEvent.getTimestamp()
                    );
                }
            });
        });

        // send broadcast with response delay set to 100 ('ms' I guess).
        connection.writeRequestBuilder().addItem("broadcast", "IDENTIFY_BROADCAST:/100")
            .build().execute().whenComplete((r, e) -> {
                if (e != null) {
                    e.printStackTrace();
                    return;
                }
                System.out.println("Request status " + r.getResponseCode("broadcast"));
        });

        Thread.sleep(TimeUnit.MINUTES.toMillis(1)); // wait 1 minute and quit
    }

}