From: Spiro Trikaliotis (trik-news_at_gmx.de)
Date: 2004-01-15 11:27:17
Hello,
On Thu, Jan 15, 2004 at 10:23:53AM +0100, Groepaz wrote:
> > A DB9 null-modem cable only has lines 2, 3 and 5. This means no ground.
>
> mmmh... are there really still these cheap 3wire thingies sold? i would
> assume them having atleast rts/cts aswell, maybe also dcd/dtd.
Yes, they are. Sometimes, the handshake wires are connected locally on
each side.
> > > Would a straight-through wired DE9-DE9 male-male be safer?
> >
> > No. This means you connect both the +5V power supplies with each others.
> > You run a risk to blow one.
>
> mmmh no, you probably wont blow the powersupplies ... but the possible difference
> in static voltage potential/level is always a problem when you connect two devices
> that way. (ie, its always recommended to connect ground, but not the VCC). it
> might result into strange behaviour with the two circuits in the powersupplies
> trying to regulate the current coming from each other :)
If you connect both C64 into different outlets, connected to different
phases, then I won't be sure that there will be no damage.
In a company I once worked, I remember people talking about something like this, resulting in
a cross current of some Ampere in an installation. This was not very
good. ;-)
I'm not an electronics engineer, but from my understanding, this is even
more critical if you have PE and N connected in your house installation,
which is the case in many old houses.
So, from my (limited!) understanding, this should be avoided.
Spiro.
--
Spiro R. Trikaliotis
http://www.trikaliotis.net/
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