I have client who inherited a system where RTI RKM-1 Keypad(s) were wired direct to a Elan S66A Multi-Zone Amp zones.

The original integrator is no longer around and the client has since moved the system to a new location of the house.

Any experienced RTI integrator can enlighten me on how this is possible? Are the RKM-1 controlling the Elan S66A over IR or RS-485? What is the pin-out mapping?