20 Aug
2011
20 Aug
'11
1:02 p.m.
On 08/20/2011 02:04 PM, Tony Duell wrote:
[RS232]
Yes, I agree in principle, but in the wild there are really very few
machines that require any of the handshaking lines to be used, and if
you're trying to get a console port talking as quickly as possible (say,
at a customer site) then my approach really is the way to go. Plug,
doesn't work, re-plug, works. I can do that in less time than it takes
to fish the breakout box out of the tool bag.
I personally use a slightly different procedure in practice. I use
one of the quick-checkers that you describe, though, the one with seven
LEDs. I connect it inline, check to see that both TxD and RxD are being
driven (at any state, just ensure they're being driven), and if only one
is, insert a null modem. 99% of the time, that gets things talking
right away. For the remaining 1%, I always keep a breakout box handy.
-Dave
--
Dave McGuire
Port Charlotte, FL
Ignore the standard, and leave the break-out
box in the drawer.
After years of practically memorizing the (horrible) standard and trying
to do things "by the book" analytically, etc, I refer to it as "RS-232
in-your-face" rather than "interface".
It's odd... I would give the opposite advice. Since I started using a
breakout box (or similar) to see just what the devices were doing I find
I can wirte a serial cable and get it to work first time (at least most
of the time :-)).