However, until now, I have not really managed to work out a good use for how the keypad can be part of the system. But I have been working on that.
We now have clear display of inputs that trigger alarm, or inhibit setting, or faults, or tampers. We have setting the alarm, and unsetting using a PIN. Yay!
The way it all works is down to a small PCB, designed to fit inside the case of the display. It works off the same 12V supply, and provides RS485 to the keypad/display.