There is a microcontroller powered by one 5V power supply, other end devices (actual items irrelevant; valves, pumps, I/O, sensors, etc.) are powered by not-microcontroller-friendly voltages including 9, 12 and 24 volts. None of which share a common ground, all are controlled via relay driver and relays. The problem is to detect and verify the other power supplies are alive an well since the microcontroller cannot 'see' the status of what it is controlling (ie., even if the microcontroller has power, there is no way for it to know the end device has power; that is not 5V)
Yep. 22K is 10x too high. Seems I misplaced a decimal. But I did subtract the two 1 volt drops.
24V -2x 1V=22V; for 10mA would be a 2.2k resistor, not 22k. But still 1.4W.