Send full 8 byte of SDO message or full 4 byte of data

[pat-rohn]

In comparison to PDO's CiA301 standard expects 8 byte of the SDO message.
Some devices would abort communication, if not full length of message was sent.

Thanks again for doing this repo

[brutella]

Could you please refer to any documentation which states that this behaviour is required? Thanks.

(I couldn't find any related documentation after a quick Internet search.)

[pat-rohn]

https://www.canopensolutions.com/english/about_canopen/SDO-services.shtml

All SDO services are mapped to CAN data frames with an 8-byte length.

Official CiA301 standards are not free to download, but I'd have a snipped I could PM you.
I guess mostly it works fine without the full 8 bytes, but in some cases libraries check for it.

[brutella]

Please check out the changes I've made in the new branch refactoring. Since I don't have any CANopen devices at hand, I'm unable to fully test it – but the changes should actually fix your issue.