QUESTION:
I need an explanation of the information that is given on cables
in the RS/6000 System Overview (hardware, Software Commun., Doc,
and Training) manual. Beginning on page 1-108 the cable is given
with system end connector, signal, and device end connector.
Cable K has TxA, RxA, TxB and RxB listed under signal. What
exactly is being referred to here. Since my knowledge on cables is
limited, please provide as much detail as possible.
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A: Cable K is designed for use with EIA-422 devices. The signals that
are listed (TxA, TxB, RxA, RxB) are the four wires required for data
transmission. Bits are represented by a differential voltage across
the A and B wires, for Transmit or Receive. Thus, two lines are
required to represent data on this standard; the positive lead (A),
and the negative lead (B).
From the "RISC System/6000 Hardware Technical Reference: Options and
Devices", page 1-30:
"EIA-422A Signal Voltage Levels
The line driver produces a differential voltage in the range of
2 to 6 volts (measured at the generator interface point). The
magnitude of the differential voltage at the receiver must be in
the range of 200 millivolts to 6 volts (measured at the load
interface point). Measurements are taken at terminal A
(positive lead) with respect to terminal B (negative lead). The
following table describes the EIA-422A signal states with
respect to voltage levels."
I also recommend the introduction to Chapter 1 in this book, where the
Asynchronous adapters are discussed. The summary of standards, on
page 1-4, is particularly useful.
With respect to cable K, the following table should define the various
signal names:
Positive Negative
+----------+----------+----------+
| Transmit | TxA | TxB |
+----------+----------+----------+
| Receive | RxA | RxB |
+----------+----------+----------+
For further details on the EIA-422A signalling specifications, please
refer to the standard: EIA-422A-1978.
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This item was created from library item Q611467 BWBJV
Additional search words:
BWBJV CABLE DEC92 HARDWARE IX LISTED MEANING RISCOHW RISCSYSTEM
SIGNAL SPECIFICATIO
WWQA: ITEM: RTA000027531 ITEM: RTA000027531
Dated: 04/1996 Category: RISCOHW
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