Kondo posted the RCB-3 (and RCB-3J) robot controller command formats in a pdf file in the KHR2 support section of their website.
Of course, most RCB-3 users will probably be content to use Kondo's Heart To Heart 3 software application that is supplied with the KHR-2HV robot. However, there are some dedicated robot developers that always want to dig in deeper, or to write their own applications.
The details of the command format are particularly interesting to us since the new MANOI AT01 uses the RCB-3 controller. It could turn out to be an excellent platform to expand a robots functionality. For example, it's easy to imagine a dual controller MANOI AT01 to play soccer with the RCB-3 responsible for the robot's motions while the second CPU takes care of the vision and tactics.