Speed swith mode

1 = 3-positional switch; speeds 1, 2 and 3 are used.

2 = one button; pressing will cycle three speeds:   1 -> 2 -> 3 -> 1 -> 2 -> 3 ...

3 = ?

4 = one button; pressing will cycle four speeds:   1 -> 2 -> 3 -> 4 -> 1 -> 2 -> ...

If no button/switch installed - speed 2 is used.