PIC I/O itself can't handle 350 feet cable, nor 74HC14 is
intended to be used as receiver from this cable. Further,
please, check the idea of carring 24V DC over 300 feet
cable. The resistance of the cable may be too big.
   Better way would be to translate PIC's 0-5v output to
+5 -24v signal, using a transistor and some resistors
On the receiving side you should construct a sort of
simple level detector with switching threshold
about -24/2 = 12v.

   Anyway, you should consider a solution with feeding
the device locally and galvanic decoupling of signal
transmissiton.

Good luck.
Mike.

cflat@ev1.net wrote:
>
> Hi, I am out of my knowledge zone and thought I would pose this
> senario to the minds of this list for help. I have a PIC16F877 that
> outputs a pulse of 200us duration every 2ms (500Hz pulse). I need
> to send this pulse up to 350 feet down a cable. This cable has 3
> conductors that aren't twisted (have no choice but to use this
> cable, more wires not an option) which are 18awg stranded. Two of
> the wires are carrying 24V dc and the 3rd wire should carry the
> pulse. The pulse is ground referenced to the positive 24V lead. I
> have 5V on the receiving PCB also referenced to the 24V positive
> wire. When looking at the pulse on the scope, it is a nice clean 5V
> square pulse coming off the board. At the other end of the cable
> where it is received by another circuit board, it has a slight bit of
> ringing on the 0 to 5V transition and has a lot of ringing on
> the 5v to
> 0v transition. I had a 74HC14 on hand and put it on the receiving
> PCB and connected the signal through 2 gates but it didn't help. I
> think the ringing is too great a level. If anyone knows a good way
> to get a clean signal or clean up the signal I'd be greatful for help.
> I've been searching the net for info and it would seem a differential
> method would be preferrable but I don't have an extra wire so its not
> an option. Thanks for any help.
> Charles
>

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