4) HOW DO YOU EXTEND THE DISTANCE OF A TTL SIGNAL?
Answer: To extend the TTL signal, convert to RS485, then convert back to TTL at the other end of the RS485 cable. This way, you can extend the distance of TTL, which is only about 10 ft (3m), to a maximum of 4000 feet (1200m). SerialComm offers an externally powered RS485 to TTL converter, part no. TTL-485-5P, for this purpose.