What I want is UART not RS
1. The Arduino UNO has an asynchronous Serial Port which is known as UART Port. UART stands for Universal Asynchronous Reception and Transmission (Receiver/Transmitter).
2. The signals that are available at the DPin-0 and DPin-1 (RX, TX) pins of UNO are UART signals, and these are at TTL levels (asyncTTL).
3. The asyncTTL signal can travel at best 10-15 feet; after that they become distorted.
4. To overcome the problem of Step-3 and to allow the signal to travel up to 100-150 feet without undergoing noticeable distortion, the Radio Shack Company (many years ago) had developed the RS232 scheme in which the TTL level signal (0V =LL, 5V = LH) was transformed into (+12V = LL, -12V = LH).
We have UART signal of TTL Level
We have UART Signal of RS232 (simply RS) Level.