Re: Re: CurrentCost serial cable wanted

[Kevin Hawkins <yahoogroupskh@xxxxxxxxxxxxxx>]

A PC RS232 port still requires the +/- 12V although most PC's I accept
will work with 5V level signals.  The serial cable from CC I assume
level converts to near 12V.

Stuart Poulton wrote..
"A 3V signal will drop to 0.5v over 100 feet of cat5 cable "

Ummm.. voltage drop over a length of cable is proportional to the
current drawn. What did you use in your calculation ? That website is a
POE calculator.

An RS232 input circuit on a PC can be very high impedence and hence
create little current draw.  In theory with zero current drawn the
voltage will remain over infinite distance. However with an AC signal -
which a serial data stream is,  then the capacitance is what creates a
current impacting the voltage over distance and also related to
frequency i.e baud rate.  This causes the edges of the square wave data
to slope and characters to be misread.

K




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