Three unused solder points on an OEM board, V+, TX, 0V as shown in picture below.
Board may be designed on or along Arduino lines, not sure. Turnkey function of board is to control a small DC motor with logic to control it by either time of day or luminance ...and to be able to stop and reverse motor per a safety switch. Entire module including motor operates on 6VDC. This board has no external communications capability (wired or wireless) designed for user access (but that is what I am trying to investigate).
While my "subject question" is about "function".... what I really want to know is if I probe these (to try to understand what they show and when) what damage could I do?
I assume the V+ to 0V would give board voltage and could safely be probed Neg/Pos, but I know there is a difference between "ground" and "board 0v" and maybe probing the V+ to some test point marked GND would be safer.
The TX I assume is a data signal and perhaps works as simply as a High/Low signal (voltage or no voltage) indicating motor activity.... or it could be something smarter. I am not confident that probing that to 0V is safe either.
I'm figuring some of you PCB or Arduino folks are going to know this stuff well enough to speculate on this. Thanks in advance for any thoughts shared.