Using an existing open source project called MIOS32 (www.ucapps.de) with the addition of a driver for the FBV interface an example platform is made. For the FBV interface an additional software module is made.
Hardware wise the interface is full-duplex RS-485 based with MIDI speeds (31.25 kbaud).
Pinout of the RJ-45 connector:
3: FBV TX +
6: FBV TX -
7: FBV RX +
8: FBV RX -
Protocol wise there is a slight difference. Still it looks a lot like sysex messages but with a slight difference.
For each button, led and footcontroller the state is communicated in a single message per item. When a state of a button / controller changes, a message is send from the FBV with the new state.
The message structure is:
start of message: 0xF0
length (CMD + params): single byte.
Command: single byte.
Params: 0 to n bytes