Modbus-RTU Frame

Jung-Hyuck Huh · Jan 16, 2013

Let me know the Perfect Frame.
The following is that I have got from the Manufacturer.
I couldn't guess to make perfect frame of the following.

Request Frame
- Slave Address : 0x01
- Function : 0x03
- Starting Address HI : 0x00
- Starting Address LO : 0x00
- No. of Points HI : 0x00
- No. of Points LO : 0x04
- CRC16 HI : 0x44
- CRC16 LO : 0x09

I guess Request Frame should be either
0103000000044409 OR
0103000000042C09.
But these don't be worked at all.

Please let me know whether it is right or not.
Thanking you.

Mark · Jan 16, 2013

Hello,

> 01 03 00 00 00 04 44 09

That is correct.

Good luck,

Mark
http://peakhmi.com/

Jerry · Jan 16, 2013

>I guess Request Frame should be either
>0103000000044409 OR
>0103000000042C09.

01 03 00 00 00 04 44 09
is the frame with the correct CRC.

pvbrowser · Jan 16, 2013

> Request Frame
> - Slave Address : 0x01
> - Function : 0x03
> - Starting Address HI : 0x00
> - Starting Address LO : 0x00
> - No. of Points HI : 0x00
> - No. of Points LO : 0x04
> - CRC16 HI : 0x44
> - CRC16 LO : 0x09
>
> 0103000000044409
This seems to be ok, although i did not check if the checksum is ok?
Did you verify that the settings of the serial port are ok?
Baudrate, Start/Stop Bits, Parity

Here is our Modbus class
http://tinyurl.com/az4llre
You might compare it with your solution.

Frank O'Gorman · Jan 16, 2013

The manufacturer's version (01 03 00 00 00 04 44 09) is correct.

Andrzej · Jan 17, 2013

Hello,

Try use Modbus Tester from www.modbus.pl.
You can try different settings to find the correct.
On the spy window you can see the raw frame.

Regards,
Andrzej

santosh · Jan 17, 2013

> The manufacturer's version (01 03 00 00 00 04 44 09) is correct.

http://www.colwaysolutions.com

Jung-Hyuck Huh · Jan 17, 2013

I have set on right ways.
Could you check the following code out??
I can't check why it doesn't work on.
I already have checked the connection and data transfer with proper program. Everything is right !

====================================<pre>
Imports System.Net.Sockets
Imports System.Text

Public Class Form1

'초기값 설정
Private Sub InitForm(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
ComboBox1.Items.Add("CRC16")
ComboBox2.Items.Add("HEX")
ComboBox1.SelectedIndex = 0
ComboBox2.SelectedIndex = 0
ComboBox1.Select()

ipAdrTextBox.Text = "192.168.0.100"
portTextBox.Text = "502"

End Sub

'호출시 CRC를 계산
Private Sub GetCRC_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
CRCTextBox.Text = CrcMaker(makeCRCTextBox.Text)
End Sub

'기본 설정된 값을 사용해 통신 - Device Address 값 읽기
Private Sub AddressRead_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
Try
'CRCTextBox.Text = "ff030006000171d5"
'.Text = "0103000000044409"
'CRCTextBox.Text = "01 03 00 00 00 04 44 09"

CRCTextBox.Text = "00000000060103000000044409"
'CRCTextBox.Text = "000000000006090300000001"

'ff 03 0006 0001 71d5
'전송하는 값은 hex(16진&#49688

로 이루어져 있다

'ff - Device Address / 0xff는 Broad casting을 의미
'03 - read는 0x03, write는 0x06
'0006 - Resister Map의 Address
'0001 - read의 경우에는 읽어올 word 길이
' write의 경우에는 쓸 값
'71d5 - CRC 검사를 위한 값

'ip, port, 전송 값을 텍스트 박스에서 가져옴
Dim server_ip As String = ipAdrTextBox.Text
Dim port_num As Int32 = Convert.ToInt32(portTextBox.Text)
Dim message As String = CRCTextBox.Text

'전송할 데이터를 출력
logText.AppendText("Send Data" & vbTab & ": ")
Dim a As Byte() = StrToByte(message)
printHex(a)

'결과 데이터를 출력
logText.AppendText(vbCrLf & "Received Data" & vbTab & ": ")
Dim b As Byte() = TcpSocket(server_ip, port_num, message)
printHex(b)

'이 경우 받는 데이터
'byte 배열인 결과 데이터 b에서 b[4]값이 Device Address이다
'예> 결과값이 [FF 03 02 00 FE 10 10] 으로 나왔을 경우
'5번째 값인 FE가 원하는 Device Address 값을 나타낸다

Catch ex As Exception
MsgBox("전송 실패")

Finally
logText.AppendText(vbCrLf & vbCrLf)
logText.ScrollToCaret()

End Try
End Sub

'설정된 값으로 통신 - Channel 1의 카운터값 읽기
Private Sub CounterRead_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
Try
'CRCTextBox.Text = "FF030066000231CA"
'CRCTextBox.Text = "0103000000044409"
CRCTextBox.Text = "0103000000044409"
'FF 03 0066 0002 31CA

'ip, port, 전송 값을 텍스트 박스에서 가져옴
Dim server_ip As String = ipAdrTextBox.Text
Dim port_num As Int32 = Convert.ToInt32(portTextBox.Text)
Dim message As String = CRCTextBox.Text

'전송할 데이터를 출력
logText.AppendText("Send Data" & vbTab & ": ")
Dim a As Byte() = StrToByte(message)
printHex(a)

'결과 데이터를 출력
logText.AppendText(vbCrLf & "Received Data" & vbTab & ": ")
Dim b As Byte() = TcpSocket(server_ip, port_num, message)
printHex(b)

'이 경우 받는 데이터
'byte 배열인 결과 데이터 b에서 b[3] ~ b[7]
'b[3],b[4] -> (unsigned short) b1으로 변환, b[5], b[6] -> (unsigned short) b2로 변환한 다음
'b1 * 65535 + b2를 연산하면 결과가 나온다
'예> 결과가 [FF 03 04 00 00 00 10 E4 30]으로 나왔을 경우
'b[3], b[4] = 00 00 -> 0x0000 = 0
'b[5], b[6] = 00 10 -> 0x0010 = 16
'0 * 65535 + 16 = 16

'int32로 계산할 수도 있다
'이 경우 byte 배열을 새로 만든다
'Dim bCount As Byte = {b[6], b[5], b[4], b[3]}
'Dim nCount As Int32 = BitConverter.ToInt32(bCount, 0)
'nCount가 구하려는 값이다.

Catch ex As Exception
MsgBox("전송 실패")

Finally
logText.AppendText(vbCrLf & vbCrLf)
logText.ScrollToCaret()

End Try
End Sub

'설정된 값으로 통신 - 1번 채널의 상태 변경 (Active)

Private Sub Active_Click(sender As System.Object, e As System.EventArgs) Handles Button5.Click
Try
'CRCTextBox.Text = "FF06006500FE0D8B"
'CRCTextBox.Text = "0103000000044409"
CRCTextBox.Text = "0103000000042C09"
'FF 06 0065 00FE 0D8B

'ip, port, 전송 값을 텍스트 박스에서 가져옴
Dim server_ip As String = ipAdrTextBox.Text
Dim port_num As Int32 = Convert.ToInt32(portTextBox.Text)
Dim message As String = CRCTextBox.Text

'전송할 데이터를 출력
logText.AppendText("Send Data" & vbTab & ": ")
Dim a As Byte() = StrToByte(message)
printHex(a)

'결과 데이터를 출력
logText.AppendText(vbCrLf & "Received Data" & vbTab & ": ")
Dim b As Byte() = TcpSocket(server_ip, port_num, message)
printHex(b)

'Write 시에는 반환값이 의미없다
'제대로 전송되었는만 확인하도록 한다

Catch ex As Exception
MsgBox("전송 실패")

Finally
logText.AppendText(vbCrLf & vbCrLf)
logText.ScrollToCaret()

End Try
End Sub

'설정된 값으로 통신 - 1번 채널의 상태 변경 (Inactive)
Private Sub Inactive_Click(sender As System.Object, e As System.EventArgs) Handles Button6.Click
Try
'CRCTextBox.Text = "FF06006500FFCC4B"
'CRCTextBox.Text = "0103000000044409"
CRCTextBox.Text = "0103000000042C09"
'FF 06 0065 00FF CC4B

'ip, port, 전송 값을 텍스트 박스에서 가져옴
Dim server_ip As String = ipAdrTextBox.Text
Dim port_num As Int32 = Convert.ToInt32(portTextBox.Text)
Dim message As String = CRCTextBox.Text

'전송할 데이터를 출력
logText.AppendText("Send Data" & vbTab & ": ")
Dim a As Byte() = StrToByte(message)
printHex(a)

'결과 데이터를 출력
logText.AppendText(vbCrLf & "Received Data" & vbTab & ": ")
Dim b As Byte() = TcpSocket(server_ip, port_num, message)
printHex(b)

'Write 시에는 반환값이 의미없다
'제대로 전송되었는만 확인하도록 한다

Catch ex As Exception
MsgBox("전송 실패")

Finally
logText.AppendText(vbCrLf & vbCrLf)
logText.ScrollToCaret()

End Try
End Sub

'입력된 값을 사용해 통신
Private Sub DataSend_Click(sender As System.Object, e As System.EventArgs) Handles Button4.Click
Try
Dim server_ip As String = ipAdrTextBox.Text
Dim port_num As Int32 = Convert.ToInt32(portTextBox.Text)
Dim message As String = CRCTextBox.Text

If message.Length > 4 Then

logText.AppendText("Send Data" & vbTab & ": ")
Dim a As Byte() = StrToByte(message)
printHex(a)

logText.AppendText(vbCrLf & "Received Data" & vbTab & ": ")
Dim b As Byte() = TcpSocket(server_ip, port_num, message)
printHex(b)

End If

Catch ex As Exception
MsgBox("전송 실패")

Finally
logText.AppendText(vbCrLf & vbCrLf)
logText.ScrollToCaret()

End Try
End Sub

#Region "함수목록"

'String을 받아서 byte 배열로 변환해서 돌려준다
Public Function StrToByte(ByVal str As String) As Byte()
Dim bytes(str.Length / 2 - 1) As Byte

bytes(0) = Convert.ToByte(Microsoft.VisualBasic.Left(str, 2), 16)

For index = 3 To str.Length Step 2

bytes((index - 1) / 2) = Convert.ToByte(Mid(str, index, 2), 16)

Next

Return bytes

End Function

'지정된 ip와 포트 숫자를 사용해 메세지를 전달하고 그 결과를 바이트 배열로 받는다
Private Function TcpSocket(ByVal ip As String, ByVal port As Int32, ByVal msg As String) As Byte()

Dim tcpClient As New System.Net.Sockets.TcpClient()
tcpClient.SendTimeout = 1
tcpClient.ReceiveTimeout = 10000

tcpClient.SendBufferSize = 512
tcpClient.ReceiveBufferSize = 512

Dim bytes(tcpClient.ReceiveBufferSize) As Byte
Dim sendBytes As Byte() = StrToByte(msg)

Dim receiveBytes As Byte()

If sendBytes(1) = 6 Then
ReDim receiveBytes(sendBytes.Length)
Else
ReDim receiveBytes((sendBytes(4) * 16 + sendBytes(5)) * 2 + 4)
End If

Try
tcpClient.Connect(ip, port)

Dim networkStream As NetworkStream = tcpClient.GetStream()

If networkStream.CanWrite And networkStream.CanRead Then

networkStream.Write(sendBytes, 0, sendBytes.Length)

networkStream.Read(bytes, 0, CInt(tcpClient.ReceiveBufferSize))

For index = 0 To receiveBytes.Length - 1
receiveBytes(index) = bytes(index)
Next

tcpClient.Close()

'Return receiveBytes

Else
If Not networkStream.CanRead Then
MsgBox("Cannot read data to this stream")
tcpClient.Close()
Else
If Not networkStream.CanWrite Then
MsgBox("Cannot write data from this stream")
tcpClient.Close()
End If
End If
End If

tcpClient.Close()

Catch ex As SocketException
MsgBox("소켓 접근 오류")

Catch ex As ObjectDisposedException
MsgBox("소켓 닫힘 오류")

Catch es As Exception
MsgBox("오류 발생")
End Try

Return receiveBytes

End Function

'문자열의 CRC를 생성한다
Private Function CrcMaker(ByVal str As String) As String
Dim strtemp As String = str
If (strtemp.Length Mod 2 Or strtemp.Length = 0) Then
MessageBox.Show("잘못된 입력")
Return ""
End If

Dim usCRC As System.UInt32
Dim bytTemp As Byte
usCRC = &HFFFF
Try
For i As Integer = 0 To strtemp.Length - 2 Step 2
bytTemp = Convert.ToUInt32(strtemp.Substring(i, 2), 16)
usCRC = Convert.ToUInt32(usCRC Xor bytTemp)
For j As Integer = 1 To 8
If (usCRC And 1) Then
usCRC = usCRC >> 1
usCRC = Convert.ToUInt32(usCRC Xor Convert.ToUInt32(&HA001))
Else
usCRC = usCRC >> 1
End If
Next
Next

Return strtemp + Hex(usCRC).Substring(2, 2) + Hex(usCRC).Substring(0, 2)
Catch ex As Exception
MsgBox("문자 입력 오류")
Return ""
End Try

End Function

'바이트 배열을 헥사값으로 보여준다
Public Sub printHex(ByVal bytes As Byte())
For index = 0 To bytes.Length - 1
If Hex(bytes(index)).Length = 1 Then
logText.AppendText("0" & Hex(bytes(index)) & " ")
Else
logText.AppendText(Hex(bytes(index)) & " ")
End If
Next
End Sub

#End Region

End Class</pre>
================================================

Thread starter	Similar threads	Forum	Replies	Date
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R	Looking for Modbus RTU frame receiver for Linux	Modbus	5	Jul 16, 2010
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U	Modbus RTU frame start	Modbus	0	Oct 17, 2006
M	Modbus RTU message Frame??	Modbus	3	Feb 23, 2004

Modbus-RTU Frame

Join our Engineering Community! Sign-in with:

Modbus-RTU Frame

Jung-Hyuck Huh

Mark

Jerry

pvbrowser

Frank O'Gorman

Andrzej

santosh

Jung-Hyuck Huh

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