Alarm Keypad Protocol

[ludzinc]

Hi

I'm wanting to integrate with my home alarm panel as a part of my home automation hobby, and I figured the neatest way would be to mimic the keypad.

The connection to the panel is a 3 wire interface, two being power and ground and the third being 'data'.  The keypad is a Vertex series like the one in the link here:

https://goalarmshop.com.au/hills-burglar-alarms/reliance-alarm-keypads/security-keypad-led-16-zone

I've scoped the data pin (briefly) and the first hurdle is that the alarm panel seems to be running from -12V with respect to my house's earth.  Hooking up the scores ground cleip to the 'common' input on the keypad shorted the rail and all the blinkenlights stopped.  Thankfully all the magic smoke was kept inside and by referencing the keypads positive terminal with the scope I managed to get the attached pics.

My goole-fu isn't that strong on this topic, and I was hoping that some one could point me in the right direction.  Does this look like a typical keypad interface (I found many references to the 4-wire DSC system) or am I entering into unknown territory?  Anyone out there ever worked for Hills before and can elaborate?

Thanks in advance,

Simon

PS - Apologies if I've managed to post twice on this subject, my earlier attempt today doesn't seem to have made it (from my view).

Links to pics:

[Muttley Snickers]

It's a Hills NX series made by Caddx and they are very popular, I dont understand what you are trying to do as devices on the lan bus are individually addressed, in addition certain information in regards to security systems is a bit tricky when it comes to disclosure on a public forum even though there are plenty of them around, Austech for instance.

Your keypad is a 16 zone so your panel is most likely a NX-16.

*94-Program Code-Keypad Address ( 1 to 8 ) - * - Area Number.

Also your service light is trying to tell you something, press *2 and read the number.
It will be low battery, system clock or somebody tampering with it that shouldn't be...