Introducing the Terminal Server 720
Serial Port I/O and Cabling Options -- There are three serial I/O and cabling schemes
available for the Terminal Server 720.
- Model 721 16-port I/O module. Two 50-pin TELCO connectors provide six-wire
connections for sixteen serial devices, using a variety of wiring schemes, such as
extension cables, distribution panels. splitters, octopus cables, punch-down blocks,
modular (MODtap™) cabling, and DECconnect™ cabling. These ports support
modem control signals and communication speeds from 75 bps to 115.2 Kbps.
- Model 723 20-port I/O module. Twenty RJ-45 connectors provide eight-wire
connections for twenty serial devices using modular cabling. These ports support
modem control and concurrent hardware flow control, and communication speeds
from 75 bps to 115.2 Kbps.
- Model 724 24-port I/O module. Three 50-pin TELCO connectors provide six-wire
connections for twenty-four serial devices, using the same wiring schemes available
for the Model 721 I/O module. These ports support modem control signals and
communication speeds from 75 bps to 115.2 Kbps.
☞ When using port speeds higher than 64 kbps, you must be careful to use a cabling
scheme that minimizes the potential for "cross-talk" problems. Cabling
methods, such as punch-down blocks used in conjunction with bundled 50-wire
cables can suffer from cross-talk at these data rates. It is recommended that you
use separate shielded cables for each port (for example, a Xyplex octopus cable),
when using the TELCO I/O modules, or short cable lengths.
Network Software Loading -- If you order a server without a memory card, the unit loads its
operating software from a network host called a load server. The load server is typically a
UNIX
TM
or VAX/VMS
TM
system, a Xyplex loader (a MAXman unit, for example), or a Network
9000 product equipped with a memory card. The load server downloads a software image to the
server, over the network, whenever the server is powered on or re-initialized. The load server
can support other types of Xyplex devices as well.
0021 1-9
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General