HP J3138A, Руководство по установке

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2-5
Installing the HP AdvanceStack Internet Router
Preparing to Connect to a Network
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Signaling Standards Supported
The synchronous serial port supports the following signaling standards: EIA/
TIA-232, EIA/TIA-449, V.35, X.21, and EIA-530. You can order a DB-60 shielded
serial transition cable from HP that has the appropriate connector for the
standard you specify. The router end of the shielded serial transition cable has
a DB-60 connector, which connects to the DB-60 port on the rear panel of the
router. The other end of the serial transition cable is available with the
connector appropriate for the standard you specify. The documentation for
the device you want to connect should indicate the standard used for that
device. The synchronous serial port can be configured as DTE or DCE (except
EIA-530, which is DTE only), depending on the attached cable. To order a
shielded serial transition cable, refer to the section “Ordering Information” in
chapter 1 “HP AdvanceStack Internet Router Overview” and appendix A
“Cable Specifications”.
N O T E
All serial ports configured as DTE require external clocking from a CSU/DSU
or other DCE device.
Although attempting to manufacture your own serial cables is not recom-
mended (because of the small size of the pins on the DB-60 serial connector),
cable pinouts are provided in appendix A “Cable Specifications”.
Distance Limitations
Serial signals can travel a limited distance at any given bit rate; generally, the
slower the data rate, the greater the distance. All serial signals are subject to
distance limits, beyond which a signal degrades significantly or is completely
lost.
Table 2-3 lists the maximum speeds and distances for EIA/TIA-232 signals.
This signalling standard supports unbalanced circuits at signal speeds up to
64 Kbps.
Table 2-3. EIA/TIA-232 Speed and Distance Limitations
Data Rate (Baud) Distance (Feet) Distance (Meters)
2400 200 60
4800 100 30
9600 50 15
19200 50 15
38400 50 15
64000 25 7.6