alt Hacker NewsModbus is the equivalent of VGA connector in displays and projectors. It does have a TCP/IP version as well, but it has no security whatsoever. Or any features besides reading/writing a 16-bit value (or a single bit, charmingly referred to as "coil")
Absolutely.
I'm in the beginning stages of giving my home HVAC system an upgrade and using Modbus throughout with various adapter boards.