[RESOLVED] Don't understand this part of the manual...
Hi. I'm reading some data from a device. The device returns a total of 217 bytes.
The byte number 10 is supposed to be a "check byte", wich I think is a byte you can use to check that the data I've recieved is correct. I can read all the data, and the data makes sense except the checkbyte! I don't know how to use it. So... Can anyone out there help me? Here's the information needed to crack the code :)
The manual says that all data have to be XOR'ed with 223 before you can make sense out of it. So in the table below the first column is the byte number, the second is the "raw" data from the device and the last column is the data XOR'ed with 223.
10 first bytes:
Code:
1 - 32 - 255
2 - 32 - 255
3 - 156 - 67
4 - 202 - 21
5 - 223 - 0
6 - 223 - 0
7 - 212 - 11
8 - 219 - 4
9 - 223 - 0
10 - 70 - 153
Now, the (crappy) manual says the following about byte number 10:
Code:
check byte e-card no. Addition of bytes 3-10= Bin 0 (Mod 256)
Can anyone make any sense out of this? Thanks for all help! :)
EDIT:
Here is the data from an another device, if it helps.
Code:
1 - 32 - 255
2 - 32 - 255
3 - 51 - 236
4 - 39 - 248
5 - 223 - 0
6 - 223 - 0
7 - 207 - 16
8 - 188 - 99
9 - 223 - 0
10 - 118 - 169
Re: Don't understand this part of the manual...
It's correct. Sum bytes 3-10 after the transformation and you will end up with &H0100. Mod 256 is the same as ANDing with &H00FF. Thus:
&H00FF AND &H0100 = 0
Why they said Bin 0 is beyond me.
Re: Don't understand this part of the manual...
