I've a Brother VC-500W, and it seems to me, that there is no possibility to use it in external applications. For other models there is the b-pac sdk, but I haven't found anything similar for the VC-500W. Does anybody here have some tips or a solution how I can use it in my applications, e.g. in python, java or any other language?
Though it's been a while since this question was asked, the answer is yes! Some amazing person has reverse engineered the protocol and has provided a python module and a shell script to print from the printer. They've made the code availible here: https://m7i.org/projects/labelprinter-linux-python-for-vc-500w/ (Archive.org version) as well as a blog post explaining their reverse engineering process.
Someone has also forked the package and fixed some bugs (specifically one that caused the printer to lock up when printing a non jpeg) which is availible here: https://gitlab.com/lenchan139/labelprinter-vc500w (Archive.org version)