Initial sketch of FB setup:

Description of function blocks

Lever control:

Lever encoder FB

This function block will use the input from the installed absolute encoder to read of the position of the throttle lever. The absolute encoder will work in the range full ahead to full astern as the throttle can only be moved so far. (Aprox 140deg) This will in other words go from 100% throttle to "-100%" throttle. To make other coding easier this function block needs to convert the input from the absolute encoder to more readable 100 to -100.

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Output: Encoder signal mapped inside the 100 to -100 range.

Lever movement FB

This function block will take in a signal and move the throttle to a wished direction. Ahead or astern, or in other terms move the lever "forward" or "backwards". 

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 Input: Move leaver astern

Output: Servo motor

Main lever FB

The main FB will be connected to the Lever Encoder FB, lever movement FB and the Main FB.

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If the signal 200 is received. This means that the lever motor does not to be activated as this control panel is in control. And then we can freely move the throttle.

 Visualization:

The visualization will be a simple implementation of the control panel, and should be a basic implementation of how it is setup and looks. It needs to have all the functions as the real one. 

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When the testing is done and working, we can modify the visualization FB to be connected directly to the Main FB to be used as a normal control panel.

To be continued