Transmitting structures to the PLC

This sample shows the transfer of a structure to the PLC via ADS. The structure consists of elements of different data types:

Unpack the sample program 'Transmitting structures to the PLC': sample04.zip

• To execute the *.jar sample, the command 'java -classpath "Sample04.jar;[path to TcJavaToAds.jar] Main' must be executed in the console in the correct directory (example path: "C:TwinCAT\Ads Api\AdsToJava\*"). For this, java must be entered in the environment variables.

import de.beckhoff.jni.JNIByteBuffer;
import de.beckhoff.jni.tcads.AmsAddr;
import de.beckhoff.jni.tcads.AdsCallDllFunction;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

public class Main
{
    public static void main(String[] args)
    {
    long err;
    AmsAddr addr = new AmsAddr();

    TransferObject transfer = new TransferObject(); // See additional class
    JNIByteBuffer dataBuff = new JNIByteBuffer(19);

    // Open communication        
    AdsCallDllFunction.adsPortOpen();
    err = AdsCallDllFunction.getLocalAddress(addr);
    addr.setPort(AdsCallDllFunction.AMSPORT_R0_PLC_RTS1);

    if (err != 0) {
        System.out.println("Error: Open communication: 0x"
            + Long.toHexString(err));
    } else {
        System.out.println("Success: Open communication!");
    }

    // Use JNIByteBuffer as a backing array for ByteBuffer
    ByteBuffer bb = ByteBuffer.wrap(dataBuff.getByteArray());

    // Write elements to buffer. Litte Endian!
    bb.order(ByteOrder.LITTLE_ENDIAN);

    bb.putShort(transfer.getShortVal());
    bb.putInt(transfer.getIntVal());
    bb.put(transfer.getByteVal());
    bb.putDouble(transfer.getDoubleVal());
    bb.putFloat(transfer.getFloatVal());

    // Write struct to PLC
    err = AdsCallDllFunction.adsSyncWriteReq(addr,
        0x4020,     // Index Group
        0x0,    // Index Offset
        19,
        dataBuff);
    if(err!=0) { 
        System.out.println("Error: Write request: 0x" 
            + Long.toHexString(err)); 
    } else {
        System.out.println("Success: Write struct!");
    }

    // Close communication
    err = AdsCallDllFunction.adsPortClose();
    if(err!=0) { 
        System.out.println("Error: Close Communication: 0x" 
            + Long.toHexString(err)); 
    }
    }
}

The object to be transferred:

public class TransferObject
{
    private short shortVal;
    private int intVal;
    private byte byteVal;
    private double doubleVal;
    private float floatVal;

    public TransferObject()
    {
    this.shortVal = Short.MAX_VALUE;
    this.intVal = Integer.MIN_VALUE;
    this.byteVal = 3;
    this.doubleVal = 4.1234;
    this.floatVal = 5.4321f;
    }

    public short getShortVal() {
    return shortVal;
    }
    public int getIntVal() {
    return intVal;
    }
    public byte getByteVal() {
    return byteVal;
    }
    public double getDoubleVal() {
    return doubleVal;
    }
    public float getFloatVal() {
    return floatVal;
    }
}