Can you explain the following code, especially used in the calibration method?? Can you carefully reading the, thank you,

 Private Sub SendInstruction () 

Dim As Integer I 
Dim j As Integer 
Dim ByteHigh As Byte 
Dim ByteLow As Byte 
Dim High As Integer 
Dim low As Integer 

ByteHigh=& amp; HFF 
ByteLow=& amp; HFF 

For I=0 To 5 
Xor ByteLow ByteLow=Instruction (I) 
For j=1 To 8 
Low=ByteLow And & amp; H1 
If low=1 Then 

High=ByteHigh And & amp; H1 
If High=1 Then 
ByteHigh=((ByteHigh - 1)/2) And & amp; H7F 
ByteLow=((ByteLow - 1)/2) Or & amp; H80 
The Else 
ByteHigh=(ByteHigh/2) And & amp; H7F 
ByteLow=((ByteLow - 1)/2) And & amp; H7F 
End the If 

ByteHigh=ByteHigh Xor & amp; HA0 
ByteLow=ByteLow Xor & amp; H1 

Else 'if check code low byte on the right side of the first bit of 0 

High=ByteHigh And & amp; H1 
If High=1 Then 
ByteHigh=((ByteHigh - 1)/2) And & amp; H7F 
ByteLow=(ByteLow/2) Or & amp; H80 
The Else 
ByteHigh=(ByteHigh/2) And & amp; H7F 
ByteLow=(ByteLow/2) And & amp; H7F 
End the If 
End the If 

Next j 
Next I 

Instruction (6) check code=ByteLow 'low byte 
Instruction (7) check code=ByteHigh 'high byte 
MSComm. OutBufferCount=0 'empty output register 

MSComm. The Output to the Output buffer=Instruction 'Output Instruction 
End Sub 

CodePudding user response:

This should be the IP class check


1, the checksum field is set to 0;
2, the IP header of every 16 bit binary sum;
3, if you don't to 0 and 16 bit high, will be 16 bit and 16 bit high and low together repeatedly, until the high and 16 bit is 0, thereby gaining a 16 bit value;
4, the 16 bit value will be taken against, deposited in the checksum field,

Serial port general check. Not very accurate check method, it is mainly used for serial communication.

CodePudding user response:

When receiving bag need to confirm the header, check whether the head is wrong, the algorithm step up 2, 3, and then judge whether the results of the invert is 0, is right, or wrong,