Ademco Vista Alarm Integration

I recently sold my house, which had a Vista 15P panel installed. I used an AlarmDecoder to interface the system with Home Assistant, and it worked great. The only issue I encountered was that the motion detectors wouldn’t function when the system was Armed for Stay/Instant/Night.

We’re in the process of building a new home, and I’ve wired everything I can (trying to avoid wireless). The builder installed a Vista 15P panel, but it only supports a maximum of 22 hardwired zones. While I could make that work, I would prefer to maintain a 1-to-1 ratio between my sensors and zones. This way, I can precisely identify which door, motion, or window has been triggered. If anyone knows of a method to expand the number of zones available on this panel, please share your insights.

After we finalize the purchase of the house, my plan is to replace the 15P with a 20P panel and incorporate three 4219 expander boards. I intend to assign my entry doors to zones 1-8, while windows and motions will be connected to the expander boards. From what I understand, as long as the zones bypassed in night mode (such as motions) are connected to an expander, I should be able to receive trigger notifications in Home Assistant even when they are bypassed. Is my understanding correct?

Thank you!

Looking for help: (BTW, motion sensors are ‘follow’ so they won’t trip in stay mode. You probably know this, though.)

My AlarmDecoder works fine when connected to a PC. It arms/disarms and is set to CON ADR 18.

When connected to HA through a Pi4 USB, it won’t arm/disarm using HA’s alarm keypad. I’ve tried typing in the 4 digit code and clicking Home or Away; I’ve tried clicking the numbers for the 4 digit code and clicking Home or Away; I’ve tried typing or clicking the code plus ‘3’ (like you do on a real keypad)

The real keypads work fine.

Alarm Decoder shows the Arm/Disarm state when a keypad is used. Alarm Decoder shows all of it sensor states and these can trigger automations (motion sensor to turn on lights, for instance). The tripped alarm state shows up on HA as well and it sends a signal to my phone.

I simply can’t arm/disarm from HA. HA is up-to-date.