Checksum evaluation bug

[horchler]

You have have a checksum bug that is corrupting the reading of data values that span more than one byte. See this line:

https://github.com/robotis-pandora/ROBOTIS-OpenCM/blob/master/OpenCM_ide/processing-head/hardware/robotis/cores/robotis/Dynamixel.cpp#L273

Additionally, I'm guessing that the version of Dynamixel.cpp in this repository may not be the same as that in the currently available version 1.0.2 of the ROBOTIS IDE as the line numbers don't match up at all (what's the deal with that?).

This issue was reported on your forums about a month ago to which I posted a detailed response when I found the cause:

http://www.robotis.com/xe/?mid=qna_en&document_srl=1140665

[Rouno]

Hi ! I've got the exact same issue and the link on robotis forum is actually dead. It's unbelievable that such a problem is still not fixed. @horchler and @robotis-pandora how can I solve this ? (I'm running opencm 1.0.2)

Thanks !

[horchler]

Unfortunately, Robotis deleted all of their forums over a year ago. I reported this bug there and to Robotis directly. They don't appear to support their software very much.

I don't recall exactly what the issue was – probably an overflow or incorrect masking. You should be able to edit Dynamixel.cpp to add some print statements to debug yourself. I'll try to dig up my specific fix tonight.

In the meantime, you might try out my DynamixelQ library, which is a better/faster replacement the Robotis library used by the OpenCM IDE (only works for OpenCM9.04 and Dynamixel 1.0 protocol): https://github.com/horchler/DynamixelQ

[Rouno]

Hi @horchler , many thanks for your help. To be honest I don't think I can dig in the code to find the error, following your advise I'll try to test DynamixelQ library and see if solve the problem. Let me know though if you can figure out what your fix was ! Best

[Rouno]

Wow @horchler your library is working fantastic ! Many thanks for it, should be the referenced one ;)

No more corruptions