J2mod / Jamod read 4 TCP slave sample

JamodJ2ModTCP

import com.ghgande.j2mod.modbus.io.ModbusTCPTransaction;
import com.ghgande.j2mod.modbus.msg.ReadMultipleRegistersRequest;
import com.ghgande.j2mod.modbus.msg.ReadMultipleRegistersResponse;
import com.ghgande.j2mod.modbus.net.TCPMasterConnection;
import java.net.InetAddress;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author zho
 */
public class TCPModbus {
    /* The important instances of the classes mentioned before */
    protected static TCPMasterConnection con = null; //the conection
    protected static ModbusTCPTransaction trans = null; //the transaction
    protected static ReadMultipleRegistersRequest req = null; //the request
    protected static ReadMultipleRegistersResponse res = null; //the response
    /* Variables for storing the parameters */
    protected static InetAddress addr = null; //the slave's address
    protected static final int port = 3000;
    protected static final int ref = Integer.parseInt("011E", 16); //the reference; offset where to start reading from
    protected static final int count = 1; //the number of DI's to read
    protected static final int repeat = 1; //a loop for repeating the transaction

    /**
     * @param args the command line arguments
     */
    public static void callTCPModbus() {
        try {
            addr = InetAddress.getByName("127.0.0.1");
            //2. Open the connection
            con = new TCPMasterConnection(addr);
            con.setPort(port);
            con.connect();
            req = new ReadMultipleRegistersRequest(ref, count);
            trans = new ModbusTCPTransaction(con);
            for (int a = 0; a < 4; a++) {
                req.setUnitID(a);
                trans.setRequest(req);
                trans.execute();
                res = (ReadMultipleRegistersResponse) trans.getResponse();
                for (int n = 0; n < res.getWordCount(); n++) {
                    System.out.println("Word " + a + "=" + res.getRegisterValue(n));
                }
            }
            //6. Close the connection
            con.close();
        } catch (Exception ex) {
            Logger.getLogger(ModbusTest.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    
}