3-4
CRBRIM-W/T
CHAPTER 3: Preparing for Installation
3.4
Interference Considerations
When you run cables for any significant distance in an electromagnetic field,
interference can occur between the field and the signals on the cables. This fact
has two implications for the construction of terminal plant cabling:
•
Plant cabling can emanate radio interference if it is unshielded for too long a
distance.
•
Strong electromagnetic interference (EMI) (e.g. lightning or radio
transmitters) can destroy the RS-232 drivers and receivers in the server.
If you use twisted-pair cables with a good distribution of grounding conductors in
your plant cabling, emitted radio interference is unlikely. If you exceed the
maximum distances, ground the conductor for each data signal; however, this
practice is not recommended.
Table 3-2. IEEE Standard RS-449 Transmission Speed Versus Distance
Baud
Rate
Distance
(Feet)
Distance
(Meters)
2400
4100
1250
4800
2050
625
9600
1025
312
19200
513
156
38400
256
78
56000
102
31
T1
50
15
The RS-449 and V.35 interfaces support data rates up to 2.048
Mbps. Exceeding this maximum is not recommended; do so at your
own risk.
!
CAUTION
