31 May
2009
31 May
'09
10:41 a.m.
Dave McGuire wrote:
On May 30, 2009, at 6:46 PM, Chris Elmquist wrote:
Was it in fact the opposite tones (i.e., mark/space reversed) or
could it have been an originate mode vs. answer mode issue? Many
(most?) modems could be switched between the two sets of tones.
It's a very primitive originate-only modem, I beleive my previous post
explained the mark-space tone behaviour the fellow was observing when he
plugged the cable in. I don't see any unexpected behaviour from (my instance
of) the modem. One would have to go through hoops to get mark/space reversed.
If there was some other problem I think it must have been a configuration issue
on the DTE/terminal-emulation end. As Chris says, his explanation was a little off.
So, you
can't see a possible set of circumstances where having the
wrong
voltage coming in the serial port could cause the frequency shift
to be
wrong?
How clever do you think the tone generator side is?
Well, as Tony replied-- I think that the RS232 input is a logic level.
It's not an analog level. So, you are going to get either the mark
tone
or the space tone and not something in between.
I think this situation was just a poor explaination of what went
wrong.
Whatever miscable situation he had caused him to generate the opposite
tone of what he was expecting but not a tone that was off frequency
from
one of the two possibilities.