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 by
Bob Perrin
Start
• Arm Yourself •
RS-485 101 • Getting
Grounded • Shielding
• Topology •
Termination • Idle-state
Biasing • Transients
• Review Time •
Sources
When you hear the phrase
"multidrop network," RS-485 is probably
the first thing that comes to mind. RS-485 has been
around as an accepted standard since 1983 and is
used in everything from point-of-sale equipment
to factory-floor automation.
Often a system integrator
or even a software engineer is given the task of
assembling the RS-485 network. The reasoning is
usually something like, "RS-485 is just a twisted
pair of wires. How hard can that be to hook up?"
The answer is, "Harder than you may think."
I've seen good engineers
install unreliable RS-485 networks. There are usually
two reasons why this happens. The first is a false
assumption that the folks who wrote the RS-485 standard
worked out all the details and tradeoffs so all
that's left to do is string a couple of wires between
each node. The second reason is ignorance of what
the standard covers.
NEXT
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THE
ART AND SCIENCE OF RS-485