Contoh Code Master Modbus RTU dengan C# (FC03)

Master Modbus RTU untuk  memberi perintah  Slave Modbus RTU  khususnya untuk function Code 03 , yaitu untuk membaca data register slave RTU microcontroller pada artikel sebelumya.

Tampilan Menu Utama

Kode program dengan C#:

//sebelumnya anda drag and drop komponen serial comm ke form dan ganti namanya menjadi  serialPort1.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace SimpleSerial
{
    public partial class Form1 : Form
    {

      
        string RxString_Respon_dari_slave;
private void buttonStart_Click(object sender, EventArgs e)
        {
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 9600;

            serialPort1.Open();
            if (serialPort1.IsOpen)
            {
                buttonStart.Enabled = false;
                buttonStop.Enabled = true;
                textBox1.ReadOnly = false;
            }
        }
 private void buttonStop_Click(object sender, EventArgs e)
        {
            if (serialPort1.IsOpen)
            {
                serialPort1.Close();
                buttonStart.Enabled = true;
                buttonStop.Enabled = false;
                textBox1.ReadOnly = true;
            }

        }
private void button2_Click(object sender, EventArgs e)
        {

            
            byte[] CRC = new byte[2];
            byte[] message = new byte[8];
            ushort start = Convert.ToUInt16(textAlamatAwal.Text);
            ushort reg_qty = Convert.ToUInt16(textJumlahRegister.Text);
            // jika port belum di open , keluar
            if (!serialPort1.IsOpen) return;
            //Clear in/out buffers:
            serialPort1.DiscardOutBuffer();
            serialPort1.DiscardInBuffer();

            message[0] = Convert.ToByte(txtalamat.Text);
            message[1] = Convert.ToByte(textFunctionCode.Text); 

            message[2] = (byte)(start >> 8);
            message[3] = (byte)start;

            message[4] = (byte)(reg_qty >> 8);
            message[5] = (byte)reg_qty;

            HitungCRC(message, ref CRC);
            message[message.Length-2] = CRC[0];
            message[message.Length-1] = CRC[1];
        //tampilkan hasil CRC ke textbox
            textCRC.Text = CRC[1].ToString() + " " + CRC[0].ToString();
            textCRCHigh.Text = CRC[1].ToString();
            textCRCLow.Text = CRC[0].ToString();
            //kirim data di buffer message ke serial port
            serialPort1.Write(message, 0, message.Length);

        }
//tampilkan data respon dari slave
 private void DisplayText(object sender, EventArgs e)
        {
textBox1.AppendText(RxString_Respon_dari_slave);

        }

        private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)
        {
            RxString_Respon_dari_slave = serialPort1.ReadExisting();

            this.Invoke(new EventHandler(DisplayText));
        }

 private void HitungCRC(byte[] message, ref byte[] CRC)
        {
           

            ushort CRCFull = 0xFFFF;
            byte CRCHigh = 0xFF, CRCLow = 0xFF;
            char CRCLSB;

            for (int i = 0; i < (message.Length) - 2; i++)
            {
                CRCFull = (ushort)(CRCFull ^ message[i]);

                for (int j = 0; j < 8; j++)
                {
                    CRCLSB = (char)(CRCFull & 0x0001);
                    CRCFull = (ushort)((CRCFull >> 1) & 0x7FFF);

                    if (CRCLSB == 1)
                        CRCFull = (ushort)(CRCFull ^ 0xA001);
                }
            }
            CRC[1] = CRCHigh = (byte)((CRCFull >> 8) & 0xFF);
            CRC[0] = CRCLow = (byte)(CRCFull & 0xFF);
        }