PS: The source code is collected from: CRC Cyclic Redundancy Check of HJT212- Developer Knowledge Base
I organized and merged them into one function, so far, I finally got this painful code.
Origin:
In the past few days, I am going to write a simple data receiving end that supports HJ212-2017 "On-line Pollutant Monitoring (Monitoring) System Data Transmission Standard" for fun. After carefully studying the text of the communication protocol, I found that the data block needs to be checked by CRC16 in the communication, so I dug out the CRC16 code from a few years ago and tested it with an example (pages 19 and 20 in the standard),
I found that the results were inconsistent. My original code:
Public Function crc16Str(s As String) As String
Dim data() As Byte
Dim ReturnData(1) As Byte
Dim CRC_Reg_Lo, CRC_Reg_Hi As Byte
Dim CL, CH As Byte
Dim SaveHi, SaveLo As Byte
Dim i, j As Integer
CRC_Reg_Lo = &HFF
CRC_Reg_Hi = &HFF 'CRC寄存器&H FF FF
CH = &HA0
CL = &H1 '多项式&H A0 01
data = StrConv(s, vbFromUnicode)
For i = 0 To UBound(data)
CRC_Reg_Lo = CRC_Reg_Lo Xor data(i) '依次和寄存器低8位进行异或运算
For j = 0 To 7
SaveHi = CRC_Reg_Hi '保存高位,是为了判断右移时是否向低位字节进1
SaveLo = CRC_Reg_Lo '保存地位,是为了判断LSB是否为0
'以下是右移'''''''''''''''''''''''''''''''''''''
CRC_Reg_Hi = CRC_Reg_Hi \ 2
CRC_Reg_Lo = CRC_Reg_Lo \ 2
If ((SaveHi And &H1) = &H1) Then
CRC_Reg_Lo = CRC_Reg_Lo Or &H80
End If
'右移完成'''''''''''''''''''''''''''''''''''''''
If ((SaveLo And &H1) = &H1) Then
CRC_Reg_Hi = CRC_Reg_Hi Xor CH
CRC_Reg_Lo = CRC_Reg_Lo Xor CL
End If
Next j
Next i
ReturnData(0) = CRC_Reg_Lo '低位
ReturnData(1) = CRC_Reg_Hi '高位
s = ""
For i = 0 To UBound(ReturnData)
s = Right("00" & Hex(ReturnData(i)), 2) & s
Next
crc16Str = s
End FunctionCheck example string:
QN=20160801085857223;ST=32;CN=1062;PW=100000;MN=010000A8900016F000169DC0;Flag=5;CP=&&RtdInterval=30&&
The result is &H0759, not &H1C80. After checking it, I found that there are many versions of CRC16. The one above belongs to the ModBus algorithm. From the online CRC calculator: CRC (Cyclic Redundancy Check) online calculation_ip33.com, pilot test All CRC16 algorithms found that the results did not match.
It seems that if this is the case, it can only be changed directly according to the C language algorithm in the HJ212 standard. In the search again, I found that the online automatic monitoring (monitoring) system data transmission standard of pollutants (HJ212-2017) - CRC data verification - Liu Siyuan - There is a Java algorithm in the blog garden http://t.csdn.cn/jGja6 , in order to quickly debug, I changed it to JS language, threw it into the browser and tried it, and the result actually matched:
<html>
<head>
</head>
<body>
<script type="text/javascript">
function strToUtf8Bytes(str) {
const utf8 = [];
for (let ii = 0; ii < str.length; ii++) {
let charCode = str.charCodeAt(ii);
if (charCode < 0x80) utf8.push(charCode);
else if (charCode < 0x800) {
utf8.push(0xc0 | (charCode >> 6), 0x80 | (charCode & 0x3f));
} else if (charCode < 0xd800 || charCode >= 0xe000) {
utf8.push(0xe0 | (charCode >> 12), 0x80 | ((charCode >> 6) & 0x3f), 0x80 | (charCode & 0x3f));
} else {
ii++;
// Surrogate pair:
// UTF-16 encodes 0x10000-0x10FFFF by subtracting 0x10000 and
// splitting the 20 bits of 0x0-0xFFFFF into two halves
charCode = 0x10000 + (((charCode & 0x3ff) << 10) | (str.charCodeAt(ii) & 0x3ff));
utf8.push(
0xf0 | (charCode >> 18),
0x80 | ((charCode >> 12) & 0x3f),
0x80 | ((charCode >> 6) & 0x3f),
0x80 | (charCode & 0x3f),
);
}
}
//兼容汉字，ASCII码表最大的值为127，大于127的值为特殊字符
for(let jj=0;jj<utf8.length;jj++){
var code = utf8[jj];
if(code>127){
utf8[jj] = code - 256;
}
}
return utf8;
}
function getCRC(data212) {
let CRC =0xFFFF;
let num =0xA001;
let inum = 0;
let sb =strToUtf8Bytes(data212);//.getBytes();
for(let j = 0; j < sb.length; j ++) {
inum = sb[j];
CRC = (CRC >> 8) & 0x00FF;
CRC ^= inum;
for(let k = 0; k < 8; k++) {
let flag = CRC % 2;
CRC = CRC >> 1;
if(flag == 1) {
CRC = CRC ^ num;
}
}
}
//console.log(CRC); 7296
return CRC.toString(16).toUpperCase(); //最后别忘了，需要的是16进制结果，Integer.toHexString()
}
console.log(getCRC('QN=20160801085857223;ST=32;CN=1062;PW=100000;MN=010000A8900016F000169DC0;Flag=5;CP=&&RtdInterval=30&&'));
document.write(getCRC('QN=20160801085857223;ST=32;CN=1062;PW=100000;MN=010000A8900016F000169DC0;Flag=5;CP=&&RtdInterval=30&&')+'<br/>');
</script>
</body>
</html>Among them, strToUtf8Bytes comes from: Implementing Java's getBytes() method in JS_kinpowoo's blog-CSDN blog .
Suddenly I was too lazy to change it to VB by myself, and in the bd search results with lower and lower search hit rates, a webpage that took 3 minutes to open: HJT212 CRC Cyclic Redundancy Check - found on the developer knowledge base There is a piece of VB code in the second half page, take it over immediately, and modify it:
Function CRC16forHJ212_2017(s As String) As String '(data() As Byte) As Long
Dim r As Long
Dim hi As Byte
Dim flag As Byte
Dim i As Long, j As Long, data() As Byte
data = StrConv(s, vbFromUnicode)
r = &HFFFF&
For j = 0 To UBound(data)
hi = r \ &H100&
hi = hi Xor data(j)
r = hi
For i = 1 To 8
flag = r And 1
r = r \ 2
If flag = 1 Then
r = r Xor &HA001&
End If
Next
Next
CRC16forHJ212_2017 = Right("0000" & Hex(r), 4)
End FunctionSeveral pieces of data were tested, and the results exactly matched those in HJ212-2017.
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This note!
Related resources (5 points): HJ212-2017 "Data Transmission Standard for Online Pollutant Monitoring (Monitoring) System"-C Document Resources-CSDN Download