Documentation and examples about jlibmodbus

[gkrananth]

i have tried serial example to read float32 holding register value. Please find the code

          	ReadHoldingRegistersRequest request = new ReadHoldingRegistersRequest();
                request.setServerAddress(slaveId);
                request.setStartAddress(offset);
                request.setQuantity(quantity);
                ReadHoldingRegistersResponse response = (ReadHoldingRegistersResponse) request.getResponse();

                m.processRequest(request);
                ModbusHoldingRegisters registers = response.getHoldingRegisters();
                for (int r : registers) {
                    System.out.println(r);
                }
                //get float
                System.out.println("PI is approximately equal to " + registers.getFloat32At(0));

i am getting ILLEGAL Data_Value error code 3. My register is floating 32 data type how do i get value for the register value of float32. Integer is working.

[kochedykov]

You get ILLEGAL Data_Value at line "m.processRequest(request);"?

[gkrananth]

yes.

[gkrananth]

appreciate if you can help me faster. Thanks

[kochedykov]

At string "m.processRequest(request);" you just request multiple holding registers (16-bit values). If a device responds you with ILLEGAL_Data_Value see the documentation on the device (memory map). Perhaps, you made a mistake in address or quantity field.

[kochedykov]

Note that reading float32 requires requesting 2 holding register.

[gkrananth]

thanks for your reply, i am getting the following error even my quantity increased to 2

ipc01@ipc01-desktop:~/Downloads$ java -jar TestRTU.jar /dev/ttyUSB5 1 3110 2
INFO: Frame sent: 01030C2600022690
INFO: Frame recv: 0183030131
com.intelligt.modbus.jlibmodbus.exception.ModbusProtocolException: ILLEGAL_DATA_VALUE: Exception Code = 3
at com.intelligt.modbus.jlibmodbus.ModbusMaster.processRequest(ModbusMaster.java:142)
at com.hdb.ModbusTestRTU.main(ModbusTestRTU.java:99)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)

[kochedykov]

You received the exception code 3 from the remote device with slaveId = 1, function code = 03. It means that the remote device cannot send you 2 valid register values with offset 0C26. You receive valid MODBUS EXCEPTION response from the remote slave and the library handle the response correctly. Can you show me the slave's memory-map?

[gkrananth]

[kochedykov]

I do not see an element with offset 3110 (0x0C26).

[gkrananth]

Please find the attachment of modscan result. Is it can help you to identify the issue?

…

On 16 February 2018 at 10:51, Vladislav Y. Kochedykov < ***@***.***> wrote: I do not see an element with offset 3110 (0x0C26). — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGy4SaEGMJof5HJk09cs-Gw56BRj3Gavks5tVRBsgaJpZM4OcgBc> .

[gkrananth]

3110 is there but my attachment is referring the float32 register data type and even 2700 is also giving same error.

[kochedykov]

please show the source code.

[gkrananth]

package com.hdb;

import com.intelligt.modbus.jlibmodbus.Modbus;
import com.intelligt.modbus.jlibmodbus.ModbusMaster;
import com.intelligt.modbus.jlibmodbus.ModbusMasterFactory;
import com.intelligt.modbus.jlibmodbus.data.ModbusHoldingRegisters;
import com.intelligt.modbus.jlibmodbus.exception.ModbusIOException;
import com.intelligt.modbus.jlibmodbus.exception.ModbusNumberException;
import com.intelligt.modbus.jlibmodbus.exception.ModbusProtocolException;
import com.intelligt.modbus.jlibmodbus.msg.request.ReadHoldingRegistersRequest;
import com.intelligt.modbus.jlibmodbus.msg.response.ReadHoldingRegistersResponse;
import com.intelligt.modbus.jlibmodbus.serial.SerialParameters;
import com.intelligt.modbus.jlibmodbus.serial.SerialPort;
import com.intelligt.modbus.jlibmodbus.serial.SerialPortException;

import jssc.SerialPortList;

/*

• Copyright (C) 2016 "Invertor" Factory", JSC

• All rights reserved

• This file is part of JLibModbus.

• Redistribution and use in source and binary forms, with or without modification,

• are permitted provided that the following conditions are met:

• 1. Redistributions of source code must retain the above copyright notice,

• this list of conditions and the following disclaimer.

• 2. Redistributions in binary form must reproduce the above copyright notice,

• this list of conditions and the following disclaimer in the documentation and/or

• other materials provided with the distribution.

• 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse

• or promote products derived from this software without specific prior written permission.

• THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,

• INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

• IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,

• OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

• OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

• OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,

• EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

• Authors: Vladislav Y. Kochedykov, software engineer.

• email: [email protected]
  */
  public class ModbusTestRTU {

  static public void main(String[] arg) throws SerialPortException {
  SerialParameters sp = new SerialParameters();
  Modbus.setLogLevel(Modbus.LogLevel.LEVEL_DEBUG);
  try {
  // you can use just string to get connection with remote slave,
  // but you can also get a list of all serial ports available at your system.
  // String[] dev_list = SerialPortList.getPortNames();
  // if there is at least one serial port at your system
  // if (dev_list.length > 0) {
  // you can choose the one of those you need
  sp.setDevice(arg[0]);
  // these parameters are set by default
  sp.setBaudRate(SerialPort.BaudRate.BAUD_RATE_19200);
  sp.setDataBits(8);
  sp.setParity(SerialPort.Parity.EVEN);
  sp.setStopBits(1);
  //you can choose the library to use.
  //the library uses jssc by default.
  //
  //first, you should set the factory that will be used by library to create an instance of SerialPort.
  //SerialUtils.setSerialPortFactory(new SerialPortFactoryRXTX());
  // JSSC is Java Simple Serial Connector
  //SerialUtils.setSerialPortFactory(new SerialPortFactoryJSSC());
  // PJC is PureJavaComm.
  //SerialUtils.setSerialPortFactory(new SerialPortFactoryPJC());
  // JavaComm is the Java Communications API (also known as javax.comm)
  //SerialUtils.setSerialPortFactory(new SerialPortFactoryJavaComm());
  //in case of using serial-to-wifi adapter
  //String ip = "192.168.0.180";//for instance
  //int port = 777;
  //SerialUtils.setSerialPortFactory(new SerialPortFactoryTcp(new TcpParameters(InetAddress.getByName(ip), port, true)));
  // you should use another method:
  //next you just create your master and use it.
  ModbusMaster m = ModbusMasterFactory.createModbusMasterRTU(sp);
  m.connect();
  while(true){

           int slaveId = Integer.parseInt(arg[1]);
           int offset = Integer.parseInt(arg[2]);
           int quantity = Integer.parseInt(arg[3]);
           //you can invoke #connect method manually, otherwise it'll be invoked automatically
           try {
           	ReadHoldingRegistersRequest request = new ReadHoldingRegistersRequest();
               request.setServerAddress(slaveId);
               request.setStartAddress(offset);
               request.setQuantity(quantity);
               ReadHoldingRegistersResponse response = (ReadHoldingRegistersResponse) request.getResponse();
  
               m.processRequest(request);
               ModbusHoldingRegisters registers = response.getHoldingRegisters();
               for (int r : registers) {
                   System.out.println(r);
               }
               //get float
               System.out.println("PI is approximately equal to " + registers.getFloat32At(0));
               System.out.println();
  
           //    m.disconnect();
           } catch (ModbusProtocolException e) {
               e.printStackTrace();
           } catch (ModbusIOException e) {
               e.printStackTrace();
           } catch (ModbusNumberException e) {
               e.printStackTrace();
           }
           Thread.sleep(1000);
           }
  

  // }
  } catch (RuntimeException e) {
  throw e;
  } catch (Exception e) {
  e.printStackTrace();
  }
  }
  }

[kochedykov]

Try using ReadInputRegisters.

[gkrananth]

But it is holding register. Is it ok to use ReadInputRegisters?

[kochedykov]

It is READ ONLY but holding register can be modified. So I guess that, actually, it is input register,

[gkrananth]

anyhow i got a error Illegal Function

[kochedykov]

I think you should ask the developer of the device you use because you send a valid request and device respond you with an exception. This issue does not relate to the library.

[gkrananth]

Hi
How to read holding register with reverse float 32 bit register value?

[kochedykov]

Hello. Holding register takes 16 bit of memory and cannot store float32. If you mean that you have to read two registers holding one float32 and each register is a bit-reversed number then you can read these two registers and apply a bit-reversal algorithm for each of the two registers. To get a floating point number you have to combine the result by bitwise operations "left-shift" and "or".