Checksum (crc_8)

vvvv beta general
1

Hi,
I’m not sure if it is a bug.

I have a device with rs232

By the description of the manufacturer there are 30 Bytes

a startbyte, 27 data bytes, a crc8 byte and a stopbyte.

When I try the example strings, it works. But when I want let vvvv generate the crc8 Checksum, vvvv does a totally diffrent result.

Is checksum crc8 proper for sure?

Check attached files.

temp_2009.04.07-21.58.28.jpg (210.7 kB)

2

And the source code for the crc8 used by the manufacturer (attached)

crc source code.jpg (41.9 kB)

3

And the patch (Version 40beta20)

checksum test.v4p (21.9 kB)

4

hello, there are 64 possibilities to calculate a crc8 checksum, vvvv uses another. CRC algorithms use a constant value called the ‘polynomial’. this is the value &H8C in your code, the result depends on this constant. vvvv uses &HD1. you could write a small plugin using your code…

5

without having a look into your patches (wheather is too good, excuse me):

you may want to try the attached module. it works reliable with BSS Soundweb Third Party Protocol.

Checksum (String XOR).zip (5.2 kB)