Home asisstant, combined with wired PLC(?) controls

I understand!
I have personally gone through 30+ years of replacing home automation hardware (original X10, Insteon, etc.). I believed, at that time, that I was choosing a well established long-term solution. It’s really hard to predict the future. :slightly_smiling_face:

Doing a quick search of this form, I found this: Creating Modbus Configuration for a Siemens LOGO!.

I also see that you have gone down this path before: Siemens logo 8.

PLCs may be more “future proof” but “smart relays” may be more appropriate. Also, as you pointed out, complexity goes up when adding a PLC. So do the potential points of failure.

My lights, alarms, cameras, etc. will continue to run with HA off-line. My automations (all in Node-Red) will not run (obviously) but all “critical” functions of my home will continue to work.

And I use a RPi4 with an SD card. Please see this post about SD Card Reliability.

So the goals are achievable. But the tradeoffs, constraints, and risks are a personal choice.