Page 10
Terminator
Terminator
The beginning and the end of the bus should be "terminated" even in systems with just a panel and a single switch. Terminators dampen reflections that could otherwise
cause data to get corrupted.
One might liken the bus to a rope with knots in it at every item on the bus. A termination could be considered to be the binding at the end of the rope to preventfraying.
SPUR
Items on the bus should be connected in sequence (no particular order needed) with no "SPURS." A Spur is any branch from the bus of more than a f ew (3) feet.
4000 ft
The bus may be up to 4000 ft long. Items must be connected in sequence. No Star Topologies allowed.
Note the way the bus has been drawn with an angle in and vertical out. This is the standard way to represent an RS 485 type data bus.
RS 485 is a Standard that describes the voltages associated with transmitting data on this type of bus.
NEVER run the bus close to current carrying conductors even if they are in conduit. 2ft away is good. NEVER EVER run the bus in the same conduit as
high voltage wires.(Even in cases where it is allowed by code.) In places with a very high Radio Frequency Field (ie near a Radio Station Antenna and
sometimes even high frequency ballasts can cause a problem) it may be necessary to use a shielded Cat 5 or run it in conduit.
Things to know about the BUS
To Next Page
Loading...
Need help?
General