## CRC calculation

Hi,

I need to calculate the CRC code from the bytes below, by using the CRC CCiTT Kermit checksum.

This is the complete code of my program: (i am using VB6)

==================================================================================================== ============
Private Sub Command1_Click()

'increase sequence byte value
Label1.Caption = Val(Label1.Caption) + 1

'+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
'begin of CRC calculation
DataCRC1 = Chr\$(bytcommand1) + Chr\$(bytcommand2) + Chr\$(bytcommand3) + Chr\$(bytcommand4) + Chr\$(bytcommand5) + Chr\$(bytcommand6) + Chr\$(bytcommand7)
'Step 1: CRC calculation for every byte of datastring (DataCRC1)
For i = 0 To 255
CRC = i
For J = 1 To 8
If (CRC And 1) = 1 Then
CRC = Fix(CRC / 2) Xor 33800
Else
CRC = Fix(CRC / 2)
End If
Next J
CRCT(i) = CRC
Next i
'Step 2: CRC calculation for all data from datastring (DataCRC1)
CRC = 0
For i = 1 To Len(DataCRC1)
HB1 = Fix(CRC / 256)
LB1 = CRC - (256 * HB1)
CRC = CRCT(LB1 Xor Asc(Mid\$(DataCRC1, i, 1))) Xor HB1
Next i
HB1 = Fix(CRC / 256): cc1hb1 = Hex(HB1): If Len(cc1hb1) = 1 Then cc1hb1 = "0" & cc1hb1
LB1 = CRC - (256 * HB1): cc1lb1 = Hex(LB1): If Len(cc1lb1) = 1 Then cc1lb1 = "0" & cc1lb1
'End CRC calculation
'+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +

On Error GoTo SendError
If MSComm1.PortOpen = True Then MSComm1.PortOpen = False
MSComm1.Settings = "19200,n,8,1"
MSComm1.CommPort = 1
Dim bytcommand(9) As Byte
'begin send data
bytcommand(0) = &H16 'SYN startbit
'CRC calculation FROM this part
bytcommand(1) = &H6
bytcommand(2) = &H9
bytcommand(3) = &HA
bytcommand(4) = &HF
bytcommand(5) = &HB
bytcommand(6) = Hex(Label1) 'sequence
bytcommand(7) = &H0
'CRC calculation TILL this part
bytcommand(8) = Hex(HB1) 'crc1
bytcommand(9) = Hex(LB1) 'crc1
'end send data

MSComm1.PortOpen = True
MSComm1.Output = bytcommand
MSComm1.PortOpen = False

Exit Sub

SendError: Exit Sub

End Sub
==================================================================================================== ===========

I am having the following bugs:

Sub or function not defined [CRCT]
and
I am not shure if i get the data for bytcommand 8 and 9 right [the CRC output]