Subj : Re: DTR Output on COM port
To   : borland.public.cpp.borlandcpp
From : Hans-Jochen Trost
Date : Mon Aug 01 2005 11:25 am

Jack,

>Actually I made a mistake in my query.  It IS pin number 4 on the DB9 
>that I was
>monitoring with my meter, and getting nothing but  0 volts.  So the 
>basic question
>remains.

no offense intended, but do you measure pin 4 against pin 5 (siganl
ground) ?  The shell may have little to do with the signal ground,
depending on how your whole setup actually looks like.

Second, do you measure on the end of a cable or directly at the output
connector of the PC?  If it is a cable, is it a straight-through or a
null-modem (computer-to-computer) cable?  A null-model cable would
swap the DTR and DSR pins ...

Cheers,             Jochen
hjtrost at microfab dot com


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