Question

你好我有crc16 Modbus的算法，但我不知道如何调用它并使用，

CONST table: ARRAY[0..255] 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);

PROCEDURE CalcCRC16 (p: pByte; nbyte: WORD; VAR CRCvalue: WORD);
VAR i: WORD;
q: pByte;
BEGIN
    q := p;
    FOR i := 1 TO nBYTE DO
    BEGIN
        CRCvalue := Hi(CRCvalue) XOR Table[ q^ XOR Lo(CRCvalue) ];
        INC(q)
    END;
END;

7e 00 00 00 00 74 00 5e 01 5a 02 20 70 11 15 20 26 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00今日00 00 00 00 00 00 00日00 00 00 00 00 00 00日00 00 00 00 00 00 00 00 00日00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

对于这些字节，它应该作为＆＃34; 79 B7＆＃34;

提前感谢大家和Stack Overflow团队！

Answer 1

这个拼图有三个缺失的部分。首先，您需要知道传递给CRCValue的{{1}}的初始值。对于Modbus CRC-16，该值为$ FFFF，found here和here。

其次，您需要知道计算CRC的结果。邮件中的所有字节？它们的连续子集？哪个子集？为此，您需要参考有关您正在使用的格式的一些文档。

第三，CRC如何存储在流中？ Big-endian还是little-endian？那么，您的CalcCRC16（可能来自流）是指16位值79 b7还是79b7？您需要再次参考文档。

搜索所有可能连续的消息子集都没有出现16位CRC。您可能在消息中错误地识别了CRC本身的位置。

如何在Delphi中使用Crc16 ModBus？

1 个答案: