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CRC16 calculation in AX or D365 FO

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Hi, can any experts here have any idea or guidance how can I develop CRC16 (checksum) calculation from a given string by using code? Many thanks.

Example in Javascript

crc16(s) {

var crcTable = [0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5,

0x60c6, 0x70e7, 0x8108, 0x9129, 0xa14a, 0xb16b,

0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 0x1231, 0x0210,

0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,

0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c,

0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401,

0x64e6, 0x74c7, 0x44a4, 0x5485, 0xa56a, 0xb54b,

0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,

0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6,

0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719, 0x8738,

0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 0x48c4, 0x58e5,

0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,

0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969,

0xa90a, 0xb92b, 0x5af5, 0x4ad4, 0x7ab7, 0x6a96,

0x1a71, 0x0a50, 0x3a33, 0x2a12, 0xdbfd, 0xcbdc,

0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,

0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03,

0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec, 0xddcd,

0xad2a, 0xbd0b, 0x8d68, 0x9d49, 0x7e97, 0x6eb6,

0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,

0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a,

0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb,

0xd10c, 0xc12d, 0xf14e, 0xe16f, 0x1080, 0x00a1,

0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,

0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c,

0xe37f, 0xf35e, 0x02b1, 0x1290, 0x22f3, 0x32d2,

0x4235, 0x5214, 0x6277, 0x7256, 0xb5ea, 0xa5cb,

0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,

0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447,

0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8,

0xe75f, 0xf77e, 0xc71d, 0xd73c, 0x26d3, 0x36f2,

0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,

0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9,

0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806, 0x6827,

0x18c0, 0x08e1, 0x3882, 0x28a3, 0xcb7d, 0xdb5c,

0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,

0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0,

0x2ab3, 0x3a92, 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d,

0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 0x7c26, 0x6c07,

0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,

0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba,

0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55, 0x5e74,

0x2e93, 0x3eb2, 0x0ed1, 0x1ef0];

var crc = 0xFFFF;

var j, i;

for (i = 0; i < s.length; i++) {

let c = s.charCodeAt(i);

if (c > 255) {

throw new RangeError();

}

j = (c ^ (crc >> 8)) & 0xFF;

crc = crcTable[j] ^ (crc << 8);

}

return ((crc ^ 0) & 0xFFFF).toString(16).toUpperCase();

}

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Martin Dráb 237,976 Most Valuable Professional on at

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I wouldn't bother implementing it from scratch by myself. You can find a plenty of exampes in C# (e.g. this one), therefore I would simply copy one of them, put them into a C# library and call it from X++ via .NET Interop.

Exact steps depend on your version of AX.

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Thanks for the link. One question, how do I pass a string and have crc16 check on the string to the C# method as I don't see the method accept string parameter.

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Martin Dráb 237,976 Most Valuable Professional on at

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This particular example takes a byte array as the input. You surely can create a method accepting a string and covert the string to a byte array, but note that the method needs to know which encoding it should use. You can either hard-code it, or pass the encoding as an additional argument. Or you keep the method as it is and let the caller code to do the conversion.

Here is an example in C# using UTF-8 encoding:

byte[] array = System.Text.Encoding.UTF8.GetBytes("abcd");

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Hi Martin,

I try using ASCII encoding for a given string text but the result of the checksum is not correct as the whole string return with the checksum is not recognize by the payment scanning. I'm trying to append a 4 char checksum to a string of given format in order to generate the QR code.

From this sample in Github github.com/.../PaynowQR by running their sample JS program the QR code is valid but not with the logic I refer from the link you shared to me. I'm not sure whether is the checksum calculation or something else.

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Martin Dráb 237,976 Most Valuable Professional on at

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l'm sorry, but I don't know why you chose ASCII and whether it's correct in your case, how the result you got differ from the expected result and so on. I also don't undestand what you mean by "the QR code is valid but not with the logic I refer from the link".

Please try to collect more information and share it with us.

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Hi Martin, the required string format that will be translated into QR code is in ASCII format for example,

00020101021226490009SG.PAYNOW010120210200905428D0301004082026020652040000530370254041.005802SG5920AXIONSPLUS PTE. LTD.6009Singapore62140110FTI00000306304AA84

The last 4 characters "AA84" is the checksum of the whole string exclude "AA8A". I've implement the C# library from the given link and pass in the string and encode it with UTF8 but I'm not able to get the same checksum "AA84". I also did try using ASCII encoding which does not work as well.

The checksum "AA84" is generated from a javascript code but I would assume crc16 check is the same regardless of what code platform.

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Martin Dráb 237,976 Most Valuable Professional on at

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There are many CRC-16 algorithms and you seem to want a particular one, but you didn't specify which one.

If I put your input to crccalc.com, I get AA8A from the algorithm called CRC-16/CCITT-FALSE. Therefore that seems to be what you need.

At the bottom of the page I mention before, you'll find links to implementation of CCITT algorithms - you can try them. Or look for other implementations on the internet.

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Hi Martin, I did implement Crc16Ccitt codes mentioned in this link sanity-free.org/.../crc_16_ccitt_in_csharp.html

and in my test runnable job I have this codes to test out but the result i'm getting is 2 weird symbol. Am I doing it correctly from D365 FO?

str postData = "00020101021226490009SG.PAYNOW010120210200905428D0301004082026020652040000530370254041.005802SG5920AXIONSPLUS PTE. LTD.6009Singapore62140110FTI00000306304";

System.Byte[] byteArray;

System.Text.Encoding encodingUTF8;

encodingUTF8 = System.Text.Encoding::get_UTF8();

byteArray = encodingUTF8.GetBytes(postData);

byteArray = ChecksumGeneratorCrc16Ccitt.Crc16Ccitt::ComputeChecksumBytes(byteArray);

info(strFmt("Text CRC: %1", encodingUTF8.GetString(byteArray)));

How should I display the return byte array if is not as below?

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Martin Dráb 237,976 Most Valuable Professional on at

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It will help if you tell us more about those weird characters.

Isn't it Byte Order Mark (BOM)?

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Hi Martin, I manage to get the result, for example AA84, one question any idea why the order is reverse? Meaning the result I'm getting is 84AA.

I've created a sample Main method for testing:

static void Main(string[] args)
{
string s = "00020101021226490009SG.PAYNOW010120210200905428D0301004082026020652040000530370254041.005802SG5920AXIONSPLUS PTE. LTD.6009Singapore62140110FTI00000306304";

byte[] crcStr = ChecksumGeneratorCrc16Ccitt.Crc16Ccitt.ComputeChecksumBytes(s);

StringBuilder hex = new StringBuilder(crcStr.Length * 2);
foreach (byte b in crcStr)
hex.AppendFormat("{0:x2}", b);

Console.WriteLine(hex.ToString());

Console.WriteLine(BitConverter.ToString(crcStr).Replace("-", ""));
}

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