I received my dual relay board,
* AtomicMarket.com: 5V Two 2 Channel Relay Module With optocoupler
* SunFounder: 2 Channel DC 5V Relay Module with Optocoupler Low Level Trigger Expansion Board
and the code to drive the relays is pretty simple and is here:
The purpose is to be able to switch +12V to a Nanolevel capacitance depth gauge and read it over RS485. I’ve been running some tests with the Nanolevel querying it over RS485, and the results have been pretty stable as temperature has varied. However in the solar powered, minimal power useage, the Nanolevel needs to be off most of the time, power switched to it when its going to be used, a pause to allow it to stabilize, and then read it over RS485.