poe, serial communication and "half-duplex"

Hello,

I found out about poe only recently. I have tried to build a data-collector application,
which queries a number of microcontrollers hidden behind one serial port, connected via
rs485 half-duplex connections. Only modest success was achieved ...

It seems to me that I have stumbled across the fact, that the rs485 network is half-duplex.
The wheel/filter combination needs to wait for the echoed characters during transmission
(allthough that could be changed to no-echo), and after that needs to read up until one
of two prompts appear in the response stream. In other words, sending and receiving data
is coupled at the wheel/filter level. Every transaction needs to be secured with retry/
timeout operations in order not to get stuck. Finally, the controllers are "quiet" unless
they receive the correct address byte. Communication must be initiated with a special byte,
on the perl side this goes as normal data (still 8 bit).


Questions:
1. Has anyone tried something similar before?
2. Is it a good idea to implement such a system in POE at all?
3. How should I go about writing a "serial-half-duplex" wheel/filter?
4. are there other/better ways to setup a poe application? Probably yes.

Any ideas, pointers are highly appreciated.

Cheers,
Erich