The purpose with the buffer board is to buffer the I/O signals to/from the Fox board, and to distribute power to the turnouts, signals and lamps on my layout and to my train recognition system. The buffer board has three connectors for power supplies, one 12 V input for the Viessmann signals, one 15 V input for the lamps and one 16 V supply for the turnouts. The turnout supply ground can be either isolated or connected to the system ground. This way, the turnout lamps can be turned on and off. The 12 V supply also supplies the Fox board, the train identification system and the electronics on the buffer board itself, via a 5 V voltage regulator.
The Fox board is connected to the buffer board via the two 2x20 pin contacts X1 and X2. The console port (serial port 0) from the Fox board is connected to X11. The buffer board contains an RS232 driver circuit and a 9-pin D-sub contact to get a standard serial interface. I intend to connect this to a control panel in the future.
Schematic
