I have minimal amount of experience with arduino but I did make a firework launcher from scratch, although it was frustrating. For my new project I would like to do the following;
Communicate over 485.
Have a pot to create a setting on the remote device.
Have an LCD to give the setpoint of the pot value, status and other information about the device.
Use a four buttons to adjust numerical values of the setpoint and send the data to the device.
I am not looking for someone to create the code for me but rather give me direction on what to research in order to achieve the goal.
Which Arduino(s)?
Why 485?
For 2 devices, why not the simpler RS-232?
Which software protocol? Standard serial? If so then find and read through Robin2 serial basics thread.
No RS-232 and RS-485 are not the same. RS-232 and RS-485 only define the hardware layer. Somewhere along he way you need to find out the software definition (protocol, data format, or what ever you prefer to call it).