Simulator parameters which have their values vary within a certain range can be controlled in two ways - using either relative or absolute value change.
In the first case, the value is changed step by step using the +/- buttons or encoders, as described on the "Rotating Encoders" page. This is incremental or relative control when the position of the actuator is not correlated with the range of values.
Another way to control numerical parameters is using position sensors connected to analog inputs, when the parameter value should follow the position of the control actuators - such as main flight controls, engine control levers, flaps or brakes handles.
Also, you can directly control such parameters as instrument lighting, trims, pointer position in some instruments (for example, radio altimeter), using analog sensors instead of rotary encoders.
Usually, a simple resistive potentiometer is used as analog sensor - a variable resistor with 3 terminals connected as a voltage divider circuit. The middle terminal of a potentiometer should be connected directly to analog input, and the two others to +5v and common GND bus.
Any suitable potentiometer with full resistance of 1k to 30k can be used. Actually you can use any pot up to 100k, But the lower the resistance, the less interference it picks up, and the circuit is more tolerant to electrical noise in the power lines. Say, 2 - 5k is fine.
The plugin converts sensor movement range into the range of dataref values and sends a new value to X-Plane every time the sensor position is changed by one step of predifined precision (sensitivity).
You can also use some photoresistive or magnetoresistive sensors as signal source for analog input, that can provide output voltage in range of 0..5v.
For example it can be a pair of photoresistors connected as voltage divider and exposed to light source that is moved toward one photocell away from another.
The full range of analog input is between 0 and +5v (0-100% in RealSimControl ), but you may have a situation when you can't use the full range of sensor movement (e.g. when a potentiometer is fixed in place and has only a fraction of its full rotation angle used for the control lever). In this case input range can vary (0..3v, or 2..4v, and so on).
The calibration function in the SimVimX plugin helps you configure such sensors properly ("Calibrate analog" menu). The plugin will then convert the partial movement ranges of your analog sensors to the full value ranges.
To assign an analog input, find a parameter in the configurator that is suitable for it, then select an analog Arduino pin.
No entry of additional parameters is required. The precision (sensitivity) and the dataref value range are pre-defined for each parameter, but can be changed with a correction config file if you need.
If you have analog sensors with partial movement range in your cockpit, use the plugin's built-in "Analog Calibration" feature to configure them properly. The corresponding analog inputs must be included in the configuration file, and the plugin must establish connection with the Arduino board first.
After pressing the "Calibrate" button, move all analog sensor handles in your Cockpit in their full range (moving each of them into min/max positions once is enough). After you've done that, press "Finish". Now, the plugin will consider the movement ranges of your analog sensors to be the full range for the purposes of value mapping.
You only need to do this once, as long as the analog sensors remain connected to the same analog inputs, as their calibration data is saved into the plugin's axis configuration file.