Richard Ellingworth
Very simple test program that transmits a message at regular intervals over an RS485 datalink. Turns off the transmitter 600 microseconds after the last byte in the transmission is put into the TX buffer. This may need adjusting. A much better solution would be to read the register that tells you when the transmitter is empty but I haven't figured this out yet.
Fork of
RS485Test
by 
Richard Ellingworth