calculate SQ and CHK for mbus command

[Zandis]

Please somebody explain me how to calculate SQ and CHK for mbus command.
Thanx.

[NokDoc]

Hi,

One of them was a bytewised xor:

Chk = QS(1)
For Ih = 2 To 12
Chk = Chk Xor QS(Ih)
Next

NokDoc

[Ice Draagon]

In Delphi (initialize MBUS):

cmdStr:=#$1F#$00#$1D#$D0#$00#$01#$04#$01#$CB
//#$CB (last byte) is the check byte, before that (#$01) is the seqNo

//seqNo (Sequence number) is always incremented by 1 everytime you
//compose an MBUS frame. Therefore, declare the variable as public.

inc(seqNo);
cmdLen:=Length(cmdStr);
cmdStr[cmdLen-1]:=Chr(seqNo); //Seq No.

//compute checksum/checkbyte from the beginning of frame upto
// the seqNo
chkByte:=0;
For i:=1 to cmdLen-1 do chkByte:=chkByte XOR Ord(cmdStr[i]);

//Store the checksum to end of the string
cmdStr[cmdLen]:=Chr(chkByte); //Checksum

You now have the InitializeMBUS ready to be sent to the COM port.

[Zandis]

Hi,

One of them was a bytewised xor:

Chk = QS(1)
For Ih = 2 To 12
Chk = Chk Xor QS(Ih)
Next

NokDoc

NokDoc.
Thanks for replaying, but can you explain more detailted? (QS, xor, what is that?)
Thanx.

[pico]

try searching
slikmik has a tool to calculate your check
sq is just any numner you like..

[Zandis]

Finally i got that.
If somebody need this:
open windows calculator in scienfist mode.
choose hex.
Type each byte step by step and after each byte press xor.
Thats easy. :)

[slikmik]

Finally i got that.
If somebody need this:
open windows calculator in scienfist mode.
choose hex.
Type each byte step by step and after each byte press xor.
Thats easy. :)


Here it is, thanks goes to some other dude who half wrote it but ive forgot who it was

[NokDoc]

NokDoc.
Thanks for replaying, but can you explain more detailted? (QS, xor, what is that?)
Thanx.

Hi,

QS is just a name of an array of bytes.

Dim QS(13) As byte
QS(1) = &h1F

I think Mr. Zandis explained quite good.

NokDoc