Personally, I have a major dislike for daisy-chained control buses like

this.

All it needs is one box at the start of the bus to go bad and you've lost control all the other boxes on the bus.

The same thing can happen with Ethernet or any communications protocol that uses a shared wire/medium. However, given the fact that RS-232 is an extremely well understood and simple technology, I don't think there is much risk in using an RS-232 daisy-chained control bus. Of course the embedded systems folks might be able to make a case for I2C or HP1B or something else that is used in industrial and laboratory control applications. --Michael Dillon