RS485/PIC18F4520-Interrupt not firing for all recieved bytes

[DavidKnott]

Thanks for your responses. I reduced the baud rate and removed checking for overruns + framing errors. This seems to have solved my problem. Still not entirely sure why it works now, but its a start !

[dhouston]

At 115200 you definitely need termination resistors at the ends of the RS485 bus. For a simple way to automatically control the TE/RE turn-around see FIG 4, p23 of...

• http://www.embeddedsys.com/subpages/..._art_RS485.pdf

[DavidKnott]

@dhouston

Thanks, I might give that a go, now that I know that the circuit is working.
I reduced the baud rate to 4800 as suggested by another member but I am still not using termination. I did read somewhere that if you are using short wiring line termination and biasing can cause more problems than it solves, however this may be only relevant for higher baud rates.

[dhouston]

Termination is not needed at low speeds but is a must at high speeds.

Here is one of the best RS485 tutorials I've seen.

• http://www.bb-elec.com/tech_articles...f_contents.asp

And, anything by Jan Axelson on the topic is worth reading. She writes with great clarity making technical topics easy to grasp.