I've got a project which will have lets say 50 Arduinos, all connected up to a single computer. Each Arduino will have rather simple devices connected to them e.g. LEDs, buttons, switches, stepper motors/servos, pots.
USB is all well and good, but I've had and currently have problems with USB devices. They drop out, they fail to recognise. If you connect a lot of them, they become unreliable also - but I'm hearing that this is mainly due to insufficient power supplies, but the former problem that I described and experience first hand is none the less enough for me to want to avoid USB.
Ethernet has problems also. Firstly, if I just want to turn on just 1 LED, i.e. manipulate a simple bit, I need to send a complex signal with massive overhead like a header etc. Using ethernet to communicate with just 1 LED is very inefficient. Secondly, I'm reading Ethernet on an Arduino drops out also due to problems with the Wiznet chip.
So my question. What alternatives are out there for interfacing a lot of Arduinos which will be controlling rather simple devices?
EDIT: I guess a lot of what I'm asking depends on the API for Arduino. Ethernet and USB are obviously already in there, but I'm guessing other methods are not available since there's no API functions for anything other than these two?