[SunRescue] RE: serial lines

[Ken Hansen]

The RS-232 standard provides for 2 channels of communication - the A/B thing is actually a normally unused part of the RS-232 standard, since few devices/applications need two comunication paths between two devices.

A normal cable, and nearly 99% of all applications, only use the primary communication link, as carried on in the "lower pins" - the Sun A/B cable simply takes the second port and maps the second link to an additional connector, transposing the pins from the "high pins" to the "low pins".

Ken

-----Original Message-----
From: rescue-request at sunhelp.org [mailto:rescue-request at sunhelp.org]
Sent: Thursday, April 05, 2001 5:50 PM
To: rescue at sunhelp.org
Subject: rescue digest, Vol 1 #1179 - 14 msgs

<snip>

Message: 3
From: "David L Kindred (Dave)" <d.kindred at telesciences.com>
Date: Thu, 5 Apr 2001 15:42:25 -0400
To: rescue at sunhelp.org
Subject: [SunRescue] Serial Port Pinouts
Reply-To: rescue at sunhelp.org

Earlier today someone was asking about the pin-out for the combined A/B
serial ports. After deleting that message, I remembered the obvious
place to look for that information: www.sunhelp.org!!!  Specifically:

    <http://www.sunhelp.org/faq/sunref2.html>

In general, a "normal" cable will let you use the A-port.  You are
usually better off with the correct splitter though, as inadvertently
connecting strange things to the B-port can cause no end of grief.