>Jim,
>
>I haven't gone through all the code, but the first char in a string has offset/index zero and not one
>
>
> replace : for (int i = 1; i < msgLength; i++)
>
> by :for (int i = 0; i < msgLength; i++)
>
>
>
>
>
>>The following VB code returns the correct value
>>
>>
>>Public Class Form1
>> ''//------------------------------------------------------------------------------------------------
>> ''// CRC Calculation routine for Kingfisher Protocol
>> ''//------------------------------------------------------------------------------------------------
>> ''unsigned int kf_crc_calc(char *string, int charnum)
>> Private Function crc_calc(ByRef strIn As String, ByRef charnum As Short) As Integer
>> Dim i As Short
>> Dim j As Short
>> Dim c As Integer
>> Dim crc As Integer
>> Dim tmp As Integer
>> Dim ch As String
>>
>> For i = 1 To charnum
>> ch = (Mid(strIn, i, 1))
>> If Len(ch) = 0 Then ch = Chr(&H0)
>> c = Asc(ch)
>> 'Debug.Print "c=" & ch & " : " & Hex(CInt(c))
>> For j = 1 To 8
>> If (crc And &H8000) > 0 Then
>>
>> crc = crc * 2
>> c = c * 2
>> If (c And &H100) Then
>>
>> crc = crc + 1
>> End If
>>
>> crc = crc Xor &H1021
>> tmp = (crc \ &H10000)
>> crc = crc - (tmp * &H10000)
>> Else
>> crc = CInt(crc * 2)
>> c = CInt(c * 2)
>> If (c And &H100) Then
>> crc = crc + 1
>> End If
>> c = (c And &HFFFF)
>> tmp = (crc \ &H10000)
>> crc = crc - (tmp * &H10000)
>> 'Debug.Print "(j): " & i & ":" & j & " c=" & Hex(c) & " crc=" & Hex(crc) & " tmp=" & tmp
>> End If
>> Next j
>> 'Debug.Print "I: " & i & ":" & j & " c=" & Hex(c) & " crc=" & Hex(crc)
>> Next i
>> Return crc
>> End Function
>>
>> Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
>> Dim TargetRTU As Integer = 0 'Should be passed in
>> Dim ViaRTU As Integer = 0 'Set to the same as target if in Direct Mode
>> Dim SourceRTU As Integer = 255 'Set to PC address
>> Dim strCommand As String
>> Dim c As Char
>> c = Chr(8) & Chr(255)
>> strCommand = Chr(TargetRTU) & _
>> Chr(8) & _
>> Chr(SourceRTU) & _
>> Chr(ViaRTU) & _
>> Chr(1) & _
>> Chr(34)
>> Me.Result.Text = Hex(crc_calc(strCommand, strCommand.Length)).ToString
>> Me.TextBox1.Text = c
>>
>> End Sub
>>End Class
>>
>>
>>
>>This is my attempt to convert to C# which does not return the same value as the VB code. Could someone help me make this conversion
>>
>>
>>using System;
>>using System.Collections.Generic;
>>using System.ComponentModel;
>>using System.Data;
>>using System.Drawing;
>>using System.Text;
>>using System.Windows.Forms;
>>
>>namespace KF_CRC_CS
>>{
>> public partial class Form1 : Form
>> {
>> public Form1()
>> {
>> InitializeComponent();
>> }
>>
>> private void btnCalcCRC_Click(object sender, EventArgs e)
>> {
>> int targetRTU = 0;
>> int ViaRTU = 0;
>> int SourceRTU = 255;
>>
>> string strCommand, tempString;
>>
>>
>> strCommand = (Convert.ToChar(targetRTU).ToString() +
>> Convert.ToChar(8).ToString() +
>> Convert.ToChar(SourceRTU).ToString() +
>> Convert.ToChar(ViaRTU).ToString() +
>> Convert.ToChar(1).ToString() +
>> Convert.ToChar(34)).ToString();
>>
>> this.txtResult.Text = calcCRC(strCommand, strCommand.Length).ToString();
>> //this.txtResult.Text = int.Parse(tempString, System.Globalization.NumberStyles.HexNumber).ToString();
>>
>>
>> }
>>
>> private int calcCRC(string msg, int msgLength)
>> {
>> int c, crc = 0, tmp;
>> string ch;
>> char C = '0';
>>
>> for (int i = 1; i < msgLength; i++)
>> {
>> ch = msg.Substring(i, 1);
>> if (ch.Length == 0)
>> C = Convert.ToChar(ch);
>> c = (int)C;
>>
>> for (int j = 1; j <= 8; j++)
>> {
>> if ((crc & 0x8000) > 0)
>> {
>> crc *= 2;
>> c *= 2;
>> if ((c & 0x100) > 0)
>> crc += 1;
>>
>> crc = crc ^ 0x1021;
>> tmp = crc % 0x10000;
>> crc = crc - tmp * 0x10000;
>> }
>> else
>> {
>> crc *= 2;
>> c *= 2;
>> if ((c & 0x100) > 0)
>> crc += 1;
>> c = c & 0xFFFF;
>> tmp = crc % 0x10000;
>> crc = crc - tmp * 0x10000;
>> }
>> }//next j
>> }//next i
>>
>> return crc;
>> }
>> }
>>}
>>Thanks for noticing. I had already tried with a zero offset with no luck. If it helps here is the original C code provided by the manufacturer.
unsigned int kf_crc_calc(BYTE *string, int charnum)
{
int i, j;
int c, crc = 0;
for (i=0; i<charnum; i++)
{ c = string[i] & 0xff;
for (j=0; j<8; j++)
{ if (crc & 0x8000)
{ crc <<= 1;
crc += (((c <<= 1) & 0x100) != 0);
crc ^= 0x1021;
}
else
{ crc <<= 1;
crc += (((c <<= 1) & 0x100) != 0);
}
}
}
return(crc);
}
int kf_crc_check(BYTE *string, int charnum)
{
unsigned int crc1 = kf_crc_calc(string, charnum);
unsigned int crc2 = (int)string[charnum] * 256 + (int)string[charnum+1];
if (crc1 == crc2) return(0);
else return(1);
}
void kf_crc_append(BYTE *string, int charnum)
{
unsigned int crc = kf_crc_calc(string, charnum);
string[charnum] = crc / 256;
string[charnum + 1] = crc % 256;
}
