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11/15/05 Ani16: Multiprotocol Design Manual © Copyright 2005 Sipex Corporation
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Figure 1. Typical WAN Environment
Many of today's routers and access equipment
are being designed with Wide Area Network
(WAN) serial ports which are able to support
various physical interface protocols or standards.
The WAN serial port may contain EIA-530,
V.35 or V.36 electrically compliant signals.
As compared with older configurations, a "multi-
protocol" serial port eliminates the need for
stocking different hardware as well as duplicate
manufacturing of the same equipment with dif-
ferent serial port connectors.
In order to allow for this flexibility, one set of
transceivers must provide the EIA-530 signals
and another set must provide the V.35 signals.
This typically requires six or more transceiver
ICs, depending on the number of physical proto-
cols implemented as well as the signaling re-
quirements used. There are a variety of trans-
ceiver IC manufacturers that offer EIA-232,
EIA-422, EIA-423 or V.35 compliant transceiv-
ers. All of these transceivers are configured to
the serial connector and programmed to only
offer the physical protocol selected. The con-
nector can vary from a DB-25 for EIA-232 and
EIA-530 to a ISO-2593 for V.35 or a custom
high density connector for all available physical
protocols. Programming the desired protocol
can either be done through hardware or soft-
ware.
There are many configurations in which one can
implement multiple physical protocols on one
serial port. In terms of serial transceivers, there
are discrete drivers and receivers which are
dedicated for each physical layer protocol. A
combination of them are needed to support the
necessary protocols. The easiest method is to
group various transceivers into a single inte-
grated circuit. Sipex offers single IC transceiv-
ers for the multi-protocol applications which
require multiple physical standards on the WAN
port. The SP500 family allows four or more
physical interface protocols to be programed on
a single IC.
Design Guide for
Multi-Protocol
Serial Ports
ANI16
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