CRC校验原理及其C语言实现-机电之家网PLC技术网

crcdata>>=1; if(crcdata&0x01) crcdata^=0xa001; } return crcdata; }

VBvbvbvbvbvbvbvvvvvvvvvvvvvvvvvvbbbbbbbbbbbbbbbbbb Private Sub Command1_Click() Dim CRC() As Byte

Dim d() As Byte '待传输数据 ReDim d(5) As Byte

d(0) = 2 '02 03 00 00 00 04 lo44 hi3A d(1) = 3 d(2) = 0 PLC

d(3) = 0 d(4) = 0

d(5) = 4 '02 03 20 40 00 04 hi2E Lo4E

CRC = CRC16(d) '调用CRC16计算函数

'CRC(0)为高位 'CRC(1)为低位 End Sub

'注意：在数据传输时CRC的低位可能在前，而高位在后。

Function CRC16(data() As Byte) As String

Dim CRC16Lo As Byte, CRC16Hi As Byte 'CRC寄存器 PLC

Dim CL As Byte, CH As Byte '多项式码&HA001

Dim SaveHi As Byte, SaveLo As Byte

Dim i As Integer Dim Flag As Integer CRC16Lo = &HFF CRC16Hi = &HFF CL = &H1 CH = &HA0

For i = 0 To UBound(data) PLC

CRC16Lo = CRC16Lo Xor data(i) '每一个数据与CRC寄存器进行异或

For Flag = 0 To 7 SaveHi = CRC16Hi SaveLo = CRC16Lo

CRC16Hi = CRC16Hi \\ 2 '高位右移一位

CRC16Lo = CRC16Lo \\ 2 '低位右移一位

If ((SaveHi And &H1) = &H1) Then '如果高位字节最后一位为1 PLC资料网

CRC16Lo = CRC16Lo Or &H80 '则低位字节右移后前面补1

End If '否则自动补0

If ((SaveLo And &H1) = &H1) Then '如果LSB为1，则与多项式码进行异或 CRC16Hi = CRC16Hi Xor CH CRC16Lo = CRC16Lo Xor CL PLC资料网

End If Next Flag Next i

Dim ReturnData(1) As Byte

ReturnData(0) = CRC16Hi 'CRC高位

ReturnData(1) = CRC16Lo 'CRC低位

CRC16 = ReturnData End Function