PWM-controlled hobby servo (1-2mS pulse evert 20mS or so) is the one-directional control I had in mind. When you are under $100 range a surprising number of servos use the same simple 1-wire protocol, even large-ish 150 kg-cm / 100W units.
Dynamixels are two-way, and they are an exact thing I'd wanted to see in search results.
Ahh, you seem to be referring to two-directional (two-way) communication, and I took it to mean rotational direction. Was imagining servos analogous to devices that simply power a motor in on/off states, so can't reverse.
Dynamixels are two-way, and they are an exact thing I'd wanted to see in search results.