Repurpose Traditional Home Security System

My home has a traditional home security system with motion sensors (LC-100-PI) and some kind of door sensor that is embeded in the frame of the door and when i open the door it pops up and i assume triggers the alarm. Does anyone have guides on using an existing traditional home security system with home assistant? I dont use that home security service but want to leverage the sensors that are already in my home.

There are a couple of projects to look at. Looking at your system I would suggest you take a look at the Konnect board. I do not use this product but it looks like it would work for you.
At least to a certain degree. Just google “Konnected” or search on Ytube.

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+1 to bertiebeez. works like a charm. I’ve been running an earlier generation of their products for a little over a year. Really fun project rewiring & hooking up/automating in HA.

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That looks Great!!!
i will check that board out

I see a few things.

1, that is a Honeywell/Ademco Vista 15 panel, you can use an Envisalink4 to connect it to HA without having to rewire it or program a new panel.

2, there appears to be some attached zone expanders or other bus attached devices wired to the panel.

3, the panel is not wired correctly, if you are using it for actual security, the wire can be cut/spliced without tripping the alarm, because the end of line resistor is not, infact, at the end of the line (sensor) it is at the beginning of the line (panel)

4, if you are using the system for security but not using a telephone hardline based monitoring service, unplug the telephone wires at the right, as it is possible to disarm it remotely if only the code is known, even if you do not have phone service, someone can just jack into the junction box.

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the system was used as security alarm by the previous owner but i have never used the home security service. The connections on the far right goes to another external device that has an antenna and looks to be a cellular device to communicate with the alarm company. Today i have everything powered off but i will look into that Envisalink4 and compare to the konnected device.


I have that Ademco vista 20 panel and I was looking at some code I found on github to connect a esp8266 to the 12volt serial bus that mimicks a keypad. How does the envislink4 work?

The EVL4 simulates one or more keypads as well, you can split the partitions as well, I will explain why that is desired.

When the V20P is armed, and a zone is tripped, the panel will not send the zone number and state to the keypads, even if they are a non-alarm zone, or a zone type like interior that triggers only when armed away. Having non-alarm zones on a different partition means the panel sends an update to that partitions keypads if the alarm zone partition is armed.

The EVL4 also has 2 important things that an ESP does not: An ethernet port, and appropriate voltage regulation to be run off the alarm power bus. This makes it a hell of a lot more reliable

AlarmDecoder. Rock solid in my experience.

Konnected is WiFi, so will never be as reliable as a wired connection (thus downgrading the wired sensors) and also seems to have no optical isolation on the board leaving it open to damage from surges and spikes (easily possible when directly connected to long wires going out to sensors).

Looks like you have a honeywell Vista panel, check out Alarmdecoder.
Have been running their ad2pi for 2+ years without an issue. Emulates a keypad so your traditional system stays intact. HA alarm panel card works great and also use cell phone presence detection automations.