RCI 3300 serial protocol

[E.B.]

I need to control a RCI 3300 central monitoring station, from KP
Electronic Systems LTD:

http://www.kpsystems.com/broshur/base/RCI3300RCI4000.pdf

I tried to contact them, buy they never answered my mails. So I made
some experiments and found:

- Serial cable format:
It's a non standard cable, isn't it?

- Connection parameters (baud rate, parity, data & stop bits, and
signals):
I guess it would be: 1200 bauds, even parity, 7 data bits, 2 stop
bits. I don't know anything about the DTR et al.

- Message format:
Ademco-685 perhaps?

Can anyone confirm or correct this information? Any link to useful
documentation would be great...

Thanks in advance

E.B.