Ok, i opened the box that contains the device, the Keybord isn't only a keyboard but contains a display and some output device, the comunication, I think, is full duplex.
1) The keybord is used to setting configuration parameter, the lcd display and other led's to output the configuration and state
2) No, the driver chip isn't visible, is covered.
3) No, but this is a good idea
4) The device contains a microprocessor or microcontroller, but all the Integrated Circuit is covered and serial number erased.
5) The data is bidirectional mode from the First device to the second and return. My plan is to generate an output from the main device to the keybord and display. Then press a key and see what data is exchanged. Then i think to generate all the possible output to build the tree of command and signal.
When I opened the main device I saw printed on board where the keyboard is connected "RS485" with connections named "A, B , +, -". Only 4 wire.
Jim, thank you for help Daniele