When you get started, just remember that to the controller the different variations of a value are the same.

so if you send \x30 (or how your controller represents a single hex byte of 30) or '0' (ASCII 0, usually represented like this...but not always) it's the same exact thing.

By dying out, perhaps the RS232 transport will die out someday, but you will most likely use the same protocol on the new transport which is probably IP. So learning RS232 isn't really accurate, you're learning protocols, data manipulation, and binary mathematics, which will always be important no matter the transport mechanism.