RS-485

[Intellisenc]

I am using RS-485/UART to communicate hundreds of feet between (3) 18F, either 4865 or 4620, and ultimately to an SN41 Bluetooth module. I either use all 4620 or all 4685 and am using the internal oscillator.

I have searched for information on baud-rate, auto baud, boot loader, oscillator, clock in an effort to learn how to reduce communication errors and increase speed, but am not finding much relating to Swordfish. Any ideas? I am thinking that baud-rate mismatch could be causing intermittent RS-485 communication.

[Jerry Messina]

That's a lot of different topics, and they don't necessarily really have much to do with swordfish per say.

I am thinking that baud-rate mismatch could be causing intermittent RS-485 communication

That could well be. The internal osc of the 4620 and 4685 aren't really accurate (+/-2% at room temp), so between two chips you could have quite a swing, and that's not accounting for any errors when using different baudrate generator settings.

What settings are you using, and what sort of errors are you seeing? Usually a baudrate mismatch will generate a Framing Error on the receiving end (but that really depends on a number of things).

[DannyScott]

Apologies in advance as I may be stating the obvious here.

Are you using proper communications cable i.e. a twisted pair / pairs? (Preferably screened over hundreds of feet)
Do you have the transmission line terminated correctly?