getting error when compiling for modbus rs232

Question

i am new in java... i am trying to read on modbus. PLC is slave device and it is configured well. my java file is unable to read modbus values.here is the code..given below. error is coming at master.init(); method. please help me in this case.

package com.mod4j;
import java.io.File;
import gnu.io.SerialPort;
import com.serotonin.io.serial.SerialParameters;
import com.serotonin.*;
import com.serotonin.modbus4j.ModbusFactory;
import com.serotonin.modbus4j.ModbusMaster;
import com.serotonin.modbus4j.code.DataType;
import com.serotonin.modbus4j.code.RegisterRange;
import com.serotonin.modbus4j.exception.ModbusInitException;
import com.serotonin.modbus4j.locator.BaseLocator;
import com.serotonin.modbus4j.locator.NumericLocator;
import com.serotonin.modbus4j.msg.ReadCoilsRequest;
import com.serotonin.modbus4j.msg.ReadCoilsResponse;
import com.serotonin.modbus4j.msg.ReadDiscreteInputsRequest;
import com.serotonin.modbus4j.msg.ReadHoldingRegistersRequest;
import com.serotonin.modbus4j.msg.ReadHoldingRegistersResponse;
import com.serotonin.modbus4j.msg.ReadInputRegistersRequest;
import com.serotonin.modbus4j.msg.ReadInputRegistersResponse;
import com.serotonin.modbus4j.msg.WriteCoilRequest;
import com.serotonin.modbus4j.msg.WriteCoilResponse;
import com.serotonin.modbus4j.msg.WriteRegistersRequest;
import com.serotonin.modbus4j.msg.WriteRegistersResponse;
import gnu.io.*;

public class Modbus4JTest
{

    public static void main(String[] args) throws Exception
    {  

   try 
   {
   SerialParameters params = new SerialParameters();
   params.setCommPortId("COM1");
   params.setBaudRate(9600);
   params.setDataBits(8);
   params.setStopBits(1);
   params.setParity(0);

   ModbusFactory modbusFactory = new ModbusFactory();
   ModbusMaster master = modbusFactory.createRtuMaster(params);
   master.setTimeout(100);
   master.setRetries(3);

   byte [] RIR,RHR,RDI,RCR;
   int slaveId=1;
   int startOffset=0;
   int numberOfRegisters=10;
   int numberOfBits=10;

   try
   {
        master.init();
        while (true) 
        {
                ReadInputRegistersRequest reqRIR = new ReadInputRegistersRequest(slaveId, startOffset, numberOfRegisters);
                System.out.println("ReadInputRegistersRequest reqRIR =" +reqRIR);
                ReadInputRegistersResponse resRIR = (ReadInputRegistersResponse) master.send(reqRIR);
                RIR = resRIR.getData();
                System.out.println("InputRegisters :" + RIR);

                ReadHoldingRegistersRequest reqRHR = new ReadHoldingRegistersRequest(slaveId, startOffset, numberOfRegisters);
                ReadHoldingRegistersResponse resRHR = (ReadHoldingRegistersResponse) master.send(reqRHR);
                RHR=resRHR.getData();
                System.out.println("HoldingRegister :" + RHR);

                ReadDiscreteInputsRequest reqRDI= new ReadDiscreteInputsRequest(slaveId, startOffset, numberOfBits);
                ReadCoilsResponse resRDI = (ReadCoilsResponse) master.send(reqRDI);
                RDI=resRDI.getData();
                System.out.println("DiscreteInput :" + RDI);

                ReadCoilsRequest reqRCR = new ReadCoilsRequest(slaveId, startOffset, numberOfBits);
                ReadCoilsResponse resRCR = (ReadCoilsResponse) master.send(reqRCR);
                RCR=resRCR.getData();   
                System.out.println("CoilResponce :" + RCR);

                short[] sdata = null;
                WriteRegistersRequest reqWR = new WriteRegistersRequest(slaveId, startOffset, sdata);
                WriteRegistersResponse resWR = (WriteRegistersResponse) master.send(reqWR);

                int writeOffset = 0;
                boolean writeValue = true;
                WriteCoilRequest reqWC = new WriteCoilRequest(slaveId, writeOffset, writeValue);
                WriteCoilResponse resWC = (WriteCoilResponse) master.send(reqWC);

                Thread.sleep(1000);
             }//end while
        }//end try
       catch (Exception e) 
       {

            e.printStackTrace();
   }//end catch

  finally 
   {
       master.destroy();
   }//end finally
 }//end try
catch (Exception e)
{
    e.printStackTrace();
}//end catch

}// end main
    }//end class Modbus4JTest

this is java file i am running.

and here are the error i have got after compiling.. please suggest what went wrong and please correct me at ... is there any step by step tutorial or any demo video please give me link at
ayyaz.nadaf@gmail.com

Exception in thread "main" java.lang.NoClassDefFoundError:      
jssc/SerialPortException
at com.serotonin.io.serial.SerialUtils.openSerialPort(SerialUtils.java:94)
at com.serotonin.modbus4j.serial.SerialMaster.init(SerialMaster.java:58)
at com.serotonin.modbus4j.serial.rtu.RtuMaster.init(RtuMaster.java:45)
at com.mod4j.Modbus4JTest.main(Modbus4JTest.java:58)
Caused by: java.lang.ClassNotFoundException: jssc.SerialPortException
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 4 more

score 0 · Answer 1 · answered Apr 11 '15 at 15:55

It appears you're using Modbus4J. It is based on jSSC (Java Simple Serial Connector) for serial communication, so make sure that jSSC is found while compiling (you may need to download it separately, since you're getting a ClassNotFoundException related to a jSSC class).

I don't know about any tutorial but I may suggest you to take a look at the Modbus4J forum archive. Here's a simple Modbus RTU example.

getting error when compiling for modbus rs232

1 Answers1