[Tfug] Yet another poser

jblais joe.blais at pti-instruments.com
Thu Sep 20 08:33:17 MST 2007


 >>
> >>
> >> Unless someone can explain a real world application of a
> >> crossover cable using POE, I call BS. This sounds way too
> >> hypothetical.
> >>
> When are you going to connect two devices supplying PoE power together?
> (such that they require conductors 4,5,7,8) You could connect two
> switches,
> but why would you connect the power then?
>


> > real world crosssover - 2 pc's direct connected without a hub.
> or GUI PC
> > direct connected to a controller where you don't want the slow
> down of the
> > rest of the world on some network chatter.
>
> This answer not specified in the context of PoE.
>
> When connecting a PC to a PoE network camera via crossover cable with
> conductors 4,5,7,8 properly connected, will the NIC power the
> camera? Don't
> think so.
>
> Still waiting to hear a real world example of crossover cable application
> using the non-ethernet TX and RX pairs for PoE....
>
> TIA
>
>

What a cable is actually used for -- POE for an invisible flying widget that
transmits the time of day -- I don't know.
The thing is, it appears that crossing comm signals makes sense, crossing
power doesn't.  So having a power crossover in your toolbox makes little
sense. Having something that looks like an RJ45, with swapped power lines or
whatever, for things other that Ethernet (ie custom RS232 stuff) doesn't
make sense to me.
These lines seem to be defined .. see link below..

http://www.alatec.com/info/other.html









More information about the tfug mailing list