VAX console and crossover cable problem

From: Tony Duell <>
Date: Fri Feb 20 17:07:55 2004

> Get one of those cheap RS-232 status monitors (just has LED's
> on several intresting signals) that are powered by the interface.
> They make diagnosing most problems easy, and don't require
> you to carry batteries around.

I'll second that recomendation!

I have some pretty nice RS232 test gear here, including a good breakout
box, an 'active' breakout box with things like the ability to send test
messages, measure bit-times, etc (there's an 8085 in there...), a
combined breakout box, current loop converter, parallel converter, EPROM
blower (!), printer, etc, a Tekky prtoocol analuser, and so on...

But I use the little box with 7 bicolour LEDs more than any of those.
It's convenient, it doesn't need me to find a mains socket or batteries,
it doesn't need settign up. I just plug it in and it tells me which, if
any, of the handshake lines are active, which pin the darn thing is
sending data on, and so on.

The other things I use a lot are my pair of home-made null-modem
adapters. One passes all handshakes (swaps RTS with CTS, DTR with DSR
strapped to DCD). The other loops all handshakes back at each side (RTS
looped to CTS, DTR looped to DSR and DCD). The second one will normally
give a device the signals it espects to start sending data. Then I can
sort out any overrun problems later.

Received on Fri Feb 20 2004 - 17:07:55 GMT

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