Mario,

You need to add the following to your program:

- set a flag (busy flag)anytime any
unit recieves a character
- perform a pseudo-random delay
of N milliseconds x random number
- check to see if the busy flag is set
if it is set then do another random
delay. Repeat until the busy flag is
not set.
If it is not set then the RS-485 bus
is free to send data out.
There is an 8 bit pseudo-random nuber generator on this web site that works very well.

Regards,

Jay