The programming cable allows you to hot rod your BBS01 & BBS02, and BBHD controller, and play with all the different setting available. See the new Bafang BBHSD 1000w drive here.
It will also work with the brand new Bafang BBHSD 1000 watt drive system as well. (See it here)
For more information check out this article: A hackers guide to programming the BBS02
You will need a windows PC and the programming software which can be found in this article: Programming guide for the BBS02
Update: Newest rewrite of the Bafang Config software (Highly recommended) https://penoff.wordpress.com/2016/01/13/e-bike-conversion-software/
Warning: Reprogramming your drive can void you warranty depending on who your dealer is. )
once I had downloaded the correct drivers to recognise the com port, worked very well.
It works great - what more could you want!