Have a look at this link to understand more about RS-232 serial links.
RS-232 is an ‘electrical’ interface, it has nothing to do with a communications or software ‘protocol’
Yet most references to The Standard have "communications" inside the first sentence much more frequently than "electrical interface." I worked with The Standard and wired circuits for a good chunk of my life, so I think I understand your point, being we generally call it the wrong thing, like "drone" is abused, because drones are dumb terminals, not hyper clocked remotly (and autonomously) conltrolled flying marvels... but no one listens. I hear you.
Yep, it’s valid to call it a communications interface, but like many words in technology, they’ve been mistranslated or oversimplified over the years to the point of being used wrongly in many instances !
One of my favourite misconceptions is ‘servos’…many people just don’t comprehend that a servo is a closed-loop control system, or even what that means.
A servo isn’t a type of motor… but it likely contains a motor, and a feedback sensor and controller.
e.g. An R/C servo is a specific self-contained ‘system’ that has a motor, position feedback, and a means of’ ‘chasing’ the input pulse stream.
I spent hours a day writing servo platters on HP793x using HP21xx (halt-preset-halt-run). Other than the reference to stepping for all platters, the modern "stepper" reference seemed odd for a while.
Unfortunately, the link you gave only is about the RS-232-C version of the standard. Earlier standards, A and B, needed a voltage range of up to +-25 volts in order to drive the cable connections with the transistors that were available at the time.
The beautiful part of the RS-232 standard is that any combination of the 25 pins can be shorted together for any length of time without damaging the equipment. Save lots of expensive equipment from klutzy technicians. Me included!
RS232 combines these standards
V24 - which defines the names and meanings of the connections
https://www.itu.int/rec/T-REC-V.24-200002-I/en
and V28 - which defines the electrical characteristics of the interfaces
the data transfer protocols are described in V.230
https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-V.230-198811-I!!PDF-E&type=items
My documentation is still on paper!
Moved here as it was not really a tutorial but just a link to a site that wanted me to sign up etc.
Fair enough - sort of.
I think the need for this type of fundamental explanation is sadly missed by many newbies.
Stack Exchange should be mandatory for learner [L] developers.
You could write a tutorial!