> When does the transmission line effect become an actual
> concern, what type of data transfer, is it more of an outgoing
> than incoming thing, or more of a high speed than a low
> speed issue?

With the little EE I know about dataline problems (helped along
by reading up on RS485 lately) I'd say it's more of a high speed
problem because the signal takes a finite time to get along the
wire (2/3 speed of light in copper or 8" per nanosecond). And
taking into account line length and capacitance you could expect
baud rate limitations at high speeds if using the wrong cable. If
you are just sending short pulses (not continuous data) these too
may be lost or attenuated. The last RS485 article I read is one of
Jan Axelson's at www.circuitcellar.com "Designing RS485 Circuits".
She goes into data lines in some detail, explaining why and when
you should terminate and the causes and effects of reflections in
cables. Worth a read, 6-page pdf, includes schematics

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