It turns out that I designed and programmed my own mini-split-AC Arduino solution that powers/reads a 2441TH Insteon thermostat. Each Arduino box has a 24VAC power supply for the thermostat, thermostat interface circuitry, IR LED drivers and a power supply for the 5VDC circuitry.
The thermostats are automated with an ISY so that I can read/control them remotely.
When a thermostat asks for heat or cooling, the Arduino box receives the 24VAC signal and then sends the appropriate IR commands to the mini-split wall unit to turn it on and off, switch heat/cool modes, Etc.
My stock mini-split remote control is non-standard so I had to reverse-engineer its infrared signal protocol. I used a LearnIR device to help with the reverse-engineering process and to create the code to program the ESP8266.
Here is one of the boxes I built:
A Closeup of the interface and ESP8266 Arduino circuitry
RJ-45 plate that holds the connectors for the thermostat and 3 IR LED emitters:
The IR LED emitters that control 3 of the 5 mini-split AC units in my shop: