Same as in our previous interfaces (ArdSimX, XPData ..), you can either use an analog input for a single rotary switch, that has a divider with several resistors, as described on this page, or a group of digital pins.
However, since SimVimCockpit supports multiple extensions, when assigning multi-position linear or rotary switches in SimVimCockpit, you can simply use a group of extended digital inputs, when one input is assigned for each switch position. So, one Arduino digital pin can be used for several rotary switches along with other buttons/switches.
Physically, a multi-position switch can be just a group of push-buttons for some equipment when each button switches this device into specific mode.
You can select any pins for one switch position in any order, but more likely you would choose one sequential set of inputs, when input pins are positioned one-by-one. Pre-defined rotary switches stricly use only sequential inputs.
Instead of several digital inputs you can use one analog input for one rotary switch. For this you need to modify a suitable rotary switch to work as analog position sensor as described on this page.
In SimVim Configurator most of the commonly used rotary switches are pre-defined as "macros" to ease configuration process. When you select a parameter from the list which is pre-defined as multiposition switch and select the first input number the configurator assigns the next several sequential inputs according to the number of positions.
If you need to assign not pre-defined rotary switches you should configure it the same way as set of momentary buttons - just select parameter for each position from the table and configure each position as "push-button" input in the configuration tool.
The problem ( read more on this page ) is when the custom virtual panel has only a couple of commands (CW/CCW) for rotary switch direction click and one read-only dataref that takes the switch position number. You can not asssign these command for your real rotary switch and can not use read-only datarefs.
This is an illustration of the fact that you don't even need to use custom planes, you can recreate almost any aircraft system using most of the standard commands and datarefs in your home cockpit.