Modbus CRC

[enzo]

Wer Kann mit helfen .
Ich soll eine Verbindung mit einem Modbus geraet durchfuehren abe es Klappt nicht.
Der CRC code , von meinem unit ist falsch.

Ich mus mit CRC=$FFFF
und der Poly=A001

Wer kann mir helfen

mein UNIT
ausblenden anzeigen Delphi-Quelltext
ausgeblendet markieren

Delphi-Quellcode:

   
Function Tform1.CRC16(InString: String) : Word;
Var
  CRC ,test   : Word;
  Index1,
  Index2  : Byte;
begin
  CRC := $FFFF;
  For Index1 := 1 to length(InString) do
  begin
    CRC := (CRC xor (ord(InString[Index1]) SHR 8));
    For Index2 := 1 to 8 do
      if ((CRC and 1) = 1) then
       CRC := (CRC shr 1) xor $A001
      else
        CRC := (CRC shr 1) ;
  end;
 CRC16 :=   (CRC and $FFFF)  ;
end;

Ich bedanke mich ihm voraus
enzo

[edit=Sharky]Delphi-Tags gesetzt und das Parsten von BBCodes aktiviert Mfg, Sharky[/edit]

[marabu]

Herzlich willkommen in der Delphi-PRAXiS, Enzo.

Vielleicht funktioniert es hiermit:

Delphi-Quellcode:

function CRC16(const s: String; const start, polynom: Word): Word;
var
  w, i, j: Word;
  b: Byte;
begin
  Result := start;
  for i := 1 to (2 + Length(S)) do begin
    if i > Length(S)
      then b := 0
      else b := Ord(S[i]);
    for J := 1 to 8 do begin
      w := (b shr 7) xor (Result shr 15);
      if (w = 1) then Result := Result xor polynom;
      Result := (Result shl 1) or w;
      b := b shl 1;
    end;
  end;
end;

Grüße vom marabu

[enzo]

Hallo marabu

danke fuer deine Hilfe, aber es kommt ein falscher wert raus !!!!

Poly=$A001
Start=$FFFF

folgenden wert gebe ich ein Hex 01040000000C und der CRC sollte F00F sein.

gruss enzo

[marabu]

Da sind schon Unterschiede zwischen CRC und CRC. Hier die tabellen-gestützte Version nach den Vorgaben des Herstellers:

Delphi-Quellcode:

const
  CRCTable: array [Byte] of Word = (
    $0000, $C0C1, $C181, $0140, $C301, $03C0, $0280, $C241,
    $C601, $06C0, $0780, $C741, $0500, $C5C1, $C481, $0440,
    $CC01, $0CC0, $0D80, $CD41, $0F00, $CFC1, $CE81, $0E40,
    $0A00, $CAC1, $CB81, $0B40, $C901, $09C0, $0880, $C841,
    $D801, $18C0, $1980, $D941, $1B00, $DBC1, $DA81, $1A40,
    $1E00, $DEC1, $DF81, $1F40, $DD01, $1DC0, $1C80, $DC41,
    $1400, $D4C1, $D581, $1540, $D701, $17C0, $1680, $D641,
    $D201, $12C0, $1380, $D341, $1100, $D1C1, $D081, $1040,
    $F001, $30C0, $3180, $F141, $3300, $F3C1, $F281, $3240,
    $3600, $F6C1, $F781, $3740, $F501, $35C0, $3480, $F441,
    $3C00, $FCC1, $FD81, $3D40, $FF01, $3FC0, $3E80, $FE41,
    $FA01, $3AC0, $3B80, $FB41, $3900, $F9C1, $F881, $3840,
    $2800, $E8C1, $E981, $2940, $EB01, $2BC0, $2A80, $EA41,
    $EE01, $2EC0, $2F80, $EF41, $2D00, $EDC1, $EC81, $2C40,
    $E401, $24C0, $2580, $E541, $2700, $E7C1, $E681, $2640,
    $2200, $E2C1, $E381, $2340, $E101, $21C0, $2080, $E041,
    $A001, $60C0, $6180, $A141, $6300, $A3C1, $A281, $6240,
    $6600, $A6C1, $A781, $6740, $A501, $65C0, $6480, $A441,
    $6C00, $ACC1, $AD81, $6D40, $AF01, $6FC0, $6E80, $AE41,
    $AA01, $6AC0, $6B80, $AB41, $6900, $A9C1, $A881, $6840,
    $7800, $B8C1, $B981, $7940, $BB01, $7BC0, $7A80, $BA41,
    $BE01, $7EC0, $7F80, $BF41, $7D00, $BDC1, $BC81, $7C40,
    $B401, $74C0, $7580, $B541, $7700, $B7C1, $B681, $7640,
    $7200, $B2C1, $B381, $7340, $B101, $71C0, $7080, $B041,
    $5000, $90C1, $9181, $5140, $9301, $53C0, $5280, $9241,
    $9601, $56C0, $5780, $9741, $5500, $95C1, $9481, $5440,
    $9C01, $5CC0, $5D80, $9D41, $5F00, $9FC1, $9E81, $5E40,
    $5A00, $9AC1, $9B81, $5B40, $9901, $59C0, $5880, $9841,
    $8801, $48C0, $4980, $8941, $4B00, $8BC1, $8A81, $4A40,
    $4E00, $8EC1, $8F81, $4F40, $8D01, $4DC0, $4C80, $8C41,
    $4400, $84C1, $8581, $4540, $8701, $47C0, $4680, $8641,
    $8201, $42C0, $4380, $8341, $4100, $81C1, $8081, $4040
  );

function ModbusCRC16(const s: String): Word;
var
  b: Byte;
  i: Integer;
begin
  Result := $FFFF;
  for i := 1 to Length(s) do
  begin
    b := Ord(s[i]) xor Result;
    Result := Result shr 8 xor CRCTable[b];
  end;
end;

Deinen Wert erhältst du so:

ShowMessage(IntToHex(not ModbusCRC16(s, $FFFF), 4)); Gute Nacht

marabu

[enzo]

Ich probiere es morgen .

Danke und eine Gute Nacht

Enzo

[enzo]

Hab es ausprobiert aber fehlanzeige???

gruss Enzo

[marabu]

Lass uns überlegen, warum es bei mir funktioniert und bei dir nicht. Als Denkhilfe habe ich ein Testprogramm angehängt.

marabu

[enzo]

Hallo marabu

Ich probiere es heute Abend .

danke

gruss Enzo

[enzo]

Hallo Marabu

Es Funktioniert, es war mein Fehler.
Aber ich bedanke mich ganz herzlich bei dir , den das war eine Grosse Hilfe.

Gruss Enzo

[sethus]

ich hatte auch eine Funktion gesucht. Diese Funktion liefert bei meinen versuchen aber den falschen Wert zurück.
daher hier meine Version der Funktion.

Delphi-Quellcode:

const
// Table of CRC values for high–order byte */
auchCRCHi : array [Byte] of Word =(
$00, $C1, $81, $40, $01, $C0, $80, $41, $01, $C0, $80, $41, $00, $C1, $81,
$40, $01, $C0, $80, $41, $00, $C1, $81, $40, $00, $C1, $81, $40, $01, $C0,
$80, $41, $01, $C0, $80, $41, $00, $C1, $81, $40, $00, $C1, $81, $40, $01,
$C0, $80, $41, $00, $C1, $81, $40, $01, $C0, $80, $41, $01, $C0, $80, $41,
$00, $C1, $81, $40, $01, $C0, $80, $41, $00, $C1, $81, $40, $00, $C1, $81,
$40, $01, $C0, $80, $41, $00, $C1, $81, $40, $01, $C0, $80, $41, $01, $C0,
$80, $41, $00, $C1, $81, $40, $00, $C1, $81, $40, $01, $C0, $80, $41, $01,
$C0, $80, $41, $00, $C1, $81, $40, $01, $C0, $80, $41, $00, $C1, $81, $40,
$00, $C1, $81, $40, $01, $C0, $80, $41, $01, $C0, $80, $41, $00, $C1, $81,
$40, $00, $C1, $81, $40, $01, $C0, $80, $41, $00, $C1, $81, $40, $01, $C0,
$80, $41, $01, $C0, $80, $41, $00, $C1, $81, $40, $00, $C1, $81, $40, $01,
$C0, $80, $41, $01, $C0, $80, $41, $00, $C1, $81, $40, $01, $C0, $80, $41,
$00, $C1, $81, $40, $00, $C1, $81, $40, $01, $C0, $80, $41, $00, $C1, $81,
$40, $01, $C0, $80, $41, $01, $C0, $80, $41, $00, $C1, $81, $40, $01, $C0,
$80, $41, $00, $C1, $81, $40, $00, $C1, $81, $40, $01, $C0, $80, $41, $01,
$C0, $80, $41, $00, $C1, $81, $40, $00, $C1, $81, $40, $01, $C0, $80, $41,
$00, $C1, $81, $40, $01, $C0, $80, $41, $01, $C0, $80, $41, $00, $C1, $81,
$40
) ;

// Table of CRC values for low–order byte */
auchCRCLo: array [Byte] of Word =(
$00, $C0, $C1, $01, $C3, $03, $02, $C2, $C6, $06, $07, $C7, $05, $C5, $C4,
$04, $CC, $0C, $0D, $CD, $0F, $CF, $CE, $0E, $0A, $CA, $CB, $0B, $C9, $09,
$08, $C8, $D8, $18, $19, $D9, $1B, $DB, $DA, $1A, $1E, $DE, $DF, $1F, $DD,
$1D, $1C, $DC, $14, $D4, $D5, $15, $D7, $17, $16, $D6, $D2, $12, $13, $D3,
$11, $D1, $D0, $10, $F0, $30, $31, $F1, $33, $F3, $F2, $32, $36, $F6, $F7,
$37, $F5, $35, $34, $F4, $3C, $FC, $FD, $3D, $FF, $3F, $3E, $FE, $FA, $3A,
$3B, $FB, $39, $F9, $F8, $38, $28, $E8, $E9, $29, $EB, $2B, $2A, $EA, $EE,
$2E, $2F, $EF, $2D, $ED, $EC, $2C, $E4, $24, $25, $E5, $27, $E7, $E6, $26,
$22, $E2, $E3, $23, $E1, $21, $20, $E0, $A0, $60, $61, $A1, $63, $A3, $A2,
$62, $66, $A6, $A7, $67, $A5, $65, $64, $A4, $6C, $AC, $AD, $6D, $AF, $6F,
$6E, $AE, $AA, $6A, $6B, $AB, $69, $A9, $A8, $68, $78, $B8, $B9, $79, $BB,
$7B, $7A, $BA, $BE, $7E, $7F, $BF, $7D, $BD, $BC, $7C, $B4, $74, $75, $B5,
$77, $B7, $B6, $76, $72, $B2, $B3, $73, $B1, $71, $70, $B0, $50, $90, $91,
$51, $93, $53, $52, $92, $96, $56, $57, $97, $55, $95, $94, $54, $9C, $5C,
$5D, $9D, $5F, $9F, $9E, $5E, $5A, $9A, $9B, $5B, $99, $59, $58, $98, $88,
$48, $49, $89, $4B, $8B, $8A, $4A, $4E, $8E, $8F, $4F, $8D, $4D, $4C, $8C,
$44, $84, $85, $45, $87, $47, $46, $86, $82, $42, $43, $83, $41, $81, $80,
$40
);


function ModbusCRC16(const s: String): Word;
var
    uchCRCHi: Byte;
    uchCRCLo: Byte;
    uIndex: Byte;
    I: Integer;
begin
    uchCRCHi := $FF;
    uchCRCLo := $FF;
    for I := 1 to Length(s) do
    begin
        uIndex := uchCRCLo xor ord(s[i]);
        uchCRCLo := uchCRCHi xor auchCRCHi[uIndex];
        uchCRCHi := auchCRCLo[uIndex];
    end;
    Result:= uchCRCHi or uchCRCLo shl 8;
end;