There are 9 buttons and 1 knob on USB focus controller.  After connecting the controller to DSLR, and get the DSLR set on real time monitoring mode, the focus can be adjusted by turning Knob. All the rest 9 buttons can be functioning by short press (hold less than 1/2 s) or long press (more than 1/2s) 

Switch USB controller to different working mode:

Hold button E, and short press button H, the indicator light will be switched from Green to Blue, to purple, which also means the working mode switched from Focus mode to Set mode, to centralizing mode.    

The Knob——In any modes, you can adjust the focus by turning the knob.

A——long-press it, we can switch the real-time mode to replay mode, press it again ,we can switch backward.

          Short press it, we can adjust the speed of focusing, the speed can be divided into 3, slow, medium, fast. One click is speed 1 (slow), double-clicks is speed 2 (medium), triple clicks is speed 3 (fast) ,such a cycle.

B——Constant smooth focus towards infinity

C——Constant smooth focus towards minimum focus distance

D——Cycles 1×/5×/10× zoom, amplification of local

Video control. Camera shutter——In the shooting mode, short press the key can change between video capture and photo shoot; Camera mode, press the key to take photoes.

E——Multi-funtion switch
Function 1:
Press the E key, press the H key can be changed to three different modes
Green    Focus point mode
Blue      Settings mode
Purple    Focus zone mode
Function 2: When the LED is purple, that means focus zone mode, short press the H key to move the focus down.

F——When the LED is purple, that means focus zone mode, short press the F key to move the focus left.

G——When the LED is purple, that means focus zone mode, short press the G key to move the focus right.
     When the LED is blue, that means setting mode, long press the G key, you can adjust the focus by turning the knob.

H——Multi-function switch
Function 1:
Press the E key, press the H key can be changed to three different modes
Green    Focus point mode
Blue      Settings mode
Purple    Focus zone mode
Function 2:
When the LED is purple, that means focus zone mode, short press the H key to move the focus up.
Function 3:
When the LED is blue, that means setting mode, long press the H key, you can adjust ISO by turning the knob.