Asynchronous Terminal Connections
The Cisco ASR 920-24SZ-IM, ASR-920-24SZ-M, ASR-920-24TZ-M Router provides a console port to
connect a terminal or computer for local console access. The port has an RJ-45 connector and supports RS-232
asynchronous data with distance recommendations specified in the IEEE RS-232 standard.
Interference Considerations
When wires are run for any significant distance, there is a risk that stray signals will be induced on the wires
as interference. If interference signals are strong, they may cause data errors or damage to the equipment.
The sections describe the sources of interference and how to minimize their effects on the Cisco ASR
920-24SZ-IM, ASR-920-24SZ-M, ASR-920-24TZ-M Router system.
Electromagnetic Interference
All the equipment powered by AC current can propagate electrical energy that can cause EMI and possibly
affect the operation of other equipment. The typical sources of EMI are equipment power cords and power
service cables from electric utility companies.
Strong EMI can destroy the signal drivers and receivers in the Cisco ASR 920-24SZ-IM, ASR-920-24SZ-M,
ASR-920-24TZ-M Router and even create an electrical hazard by causing power surges through the power
lines into installed equipment. These problems are rare, but could be catastrophic.
To resolve these problems, you need specialized knowledge and equipment that could consume substantial
time and money. However, you can ensure that you have a properly grounded and shielded electrical
environment, paying special attention to the need for electrical surge suppression.
For information about the electrode magnetic compliance standards supported on the Cisco ASR 920-24SZ-IM,
ASR-920-24SZ-M, ASR-920-24TZ-M Router, see the
Regulatory Compliance and Safety Information for
the Cisco ASR 920 Series Router
document.
Radio Frequency Interference
When electromagnetic fields act over a long distance, radio frequency interference (RFI) may be propagated.
Building wiring can often act as an antenna, receiving the RFI signals and creating more EMI on the wiring.
If you use twisted-pair cable in your plant wiring with a good distribution of grounding conductors, the plant
wiring is unlikely to emit radio interference. If you exceed the recommended distances, use a high-quality
twisted-pair cable with one ground conductor for each data signal.
Lightning and AC Power Fault Interference
If signal wires exceed the recommended cabling distances, or if signal wires pass between buildings, you
should consider the effect that a lightning strike in your vicinity might have on the Cisco ASR 920-24SZ-IM,
ASR-920-24SZ-M, ASR-920-24TZ-M Router.
The electromagnetic pulse (EMP) generated by lightning or other high-energy phenomena can couple enough
energy into unshielded conductors to damage or destroy electronic equipment. If you have previously
experienced such problems, you should consult with RFI and EMI experts to ensure that you have adequate
Cisco ASR-920-24SZ-IM, ASR-920-24SZ-M, ASR-920-24TZ-M Aggregation Services Router Hardware Installation
Guide
38
Preparing for Installation
Interference Considerations
Содержание ASR-920-24SZ-IM
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