The phrase "command dial" refers to a knob or wheel on a device that is used to give instructions or control different settings. It allows you to easily change or input commands on the device by turning or pressing the dial. Full definition
BMW's large command dial to the right of the stubby gear selector requires a learning curve — we suggest putting the vehicle in park and practicing its functions before getting under way. (kbb.com)
But bigger ships require you to stack command dials, with the top dial being revealed upon a ship's activation. (wolfsgamingblog.com)
Although the camera sets the shutter speed and aperture, you can use the Program Shift feature to adjust the shutter speed or aperture by pressing the shutter button halfway and turning the main command dial (the dial on the top front of the camera) until you get the shutter speed or aperture you want. (tomsguide.com)