Wow - this is very timely that people are asking about this. I have an EVL3 with a honeywell Vista20, and was just going to look into integrating with it (i’m a developer) in HA. I stumbled upon this because i was searching the forums trying to decide how to architect this integration.
There already exists a python project on github (HoneyAlarmServer) where this person has already essentially interpreted the low level TCP API of the EVL3 (TPI they call it), and exposed it as a REST webservice. A similar one exists for DSC (AlarmServer).
I’d like to do this integration- but it seems to me we have 3 options, and im struggling to decide which one to go with:
Rip out the raw TCP handling capabilities of these projects, put them into their own library, and use that directly in an alarm component.
modify these existing projects to work over MQTT instead, and we use the normal MQTT alarm component in HA
Implement a generic REST HA Alarm component, and use these 2 projects as-is.
Does anyone on the forums with more experience in HA have an opinion on the best way to do this? I’m leaning on option 2, as it would allow the alarm to actually raise an event within HA via MQTT, rather than do some sort of polling mechanism.