Then use RS485.
...R
Wifi? Connect to a wireless router?
Direct serial is an option but I wonder on the reliability of it over a few meters. Additionally, it directly exposes the Arduino pins to the outside world. Whereas any other method has a transceiver chip to act as a buffer between the nasty outside world and the sensitive Arduino pins. Though cheap, probably not a good solution this time.
This just seems weird to me. Those pins to the nasty outside world are what make the Arduino. Without those, the Arduino is just another computer, and not a very powerful one at that. Those sensitive pins are designed to connect to the nasty outside world.
I am definitely leaning towards RS-485. Five modules for $5, sounds good to me.
I cannot think of a design that I have in mass production where the microcontroller I/O pins are directly subjected or accessible from the outside world. There is some sort of "interface" circuitry between all of the microcontroller pins and outside world.
adwsystems:
I cannot think of a design that I have in mass production where the microcontroller I/O pins are directly subjected or accessible from the outside world.
The project I am building (mentioned in Reply #14) won't be exposing the wires to the outside world.
...R