This is possable using three lines from pic to LTC485 devices.
connect 485 with the transmit enable turned off by pull up and controlled by
the pic the resistor keeps the transmit disabled while the pic gets going.
Using one device to generate a start bit all others then listen for the start
bit and transmit their information in a time slot in sequence. I have used
this reliably up to 19.2KB and 6 devices. (the 5 which are not masters spend
most of their time listining). Dont forget to randomise the wait time if the
data bursts are a long time appart (TMR0) works, otherwise they will never
sync. Been there got the T shirt..

Steve.......