An example of Enigma Rotor turnover

The M4 Enigma (M7772/jla/1944) courtesy of David Hamer.
I have the rotors set to ALL turn over (that is.. all three that turn over, the 4th does not automatically turn over... it is set manually on all M4 Enigmas according to the daily key setting).

The rotor order is... from left to right.. V, II, I (Z E Q) and the
far left Gamma thin rotor is paired with the C reflector.
The C reflector being the left most element.
This is the normal pairing, (only one configuration is used at a time)
'Thin' B reflector (Umkehrwalze) with 'Greek' Beta rotor,
'Thin' C reflector (Umkehrwalze) with 'Greek' Gamma rotor.

Now... In the windows ... from left to right ...is:

Rotor:
Window
 
Turnover notches
Gamma
A
none
V
Z
H
II
E
M
I
Q
Y

Nine letter separation.

Now, as shown below, if I press a key, they all turn (except for the left ,4th, rotor) and I get a new set of letters in the windows... A, A, F, R
as you would expect. The left A does not turn, Z rotates to A, E rotates to F, Q rotates to R, just like the alphabet progresses.
(Position 'A' on the 'Greek' Gamma rotor emulates the 3 wheel Enigma wiring and is only rotated by the operator for a daily setting).

Note that these letters will always be in this order when - setup this
way - , with rotors in this order- even if you set the Ring setting or
'Ringstellung', to some other letter. The letters showing in the windows give no clue as to where the Datum is... and to what letter it is assigned to. What this does is assign a different
alphabet sequence to the wiring pattern associated with that rotor.
(The ring can be set to any one of 26 poitions on each rotor, in other words, each rotor will assign its wiring pattern to any of the 26 letters of the alphabet on the Ring.
(Datum as reference). The photo below shows the Datum dot aligning with the letter 'A' on the Ring. The Datum dot can be set at any letter.



Datum dot aligning with the letter 'A'

Pressing the key again will now just advance the right most rotor from 'R' to 'S'.