Re: Vsita 15P programming question

["Robert L Bass" <robertlbass@xxxxxxxxxxx>]

> I think this is what I said in my first post,
> namely that electronic components are
> listed by the manufacturers according to
> the state they are in with no external
> influence...

You got it right.  The one who was confused is one of the "professional"
installers who posts as "petem".

> I surmised that once the component was used
> in an alarm system, then the terminology went
> from manufacturer language to alarm language
> which describes the circuit...

Well, sort of.  Magnetic sensor manufacturers usually do describe the sensor
as N.O. or N.C. based on the state of the sensor with no maget around.
Control panel manufacturers usually refer to the panel zones (sensing
circuits) based on the nature of the circuit.  Thus a Normally Open magnetic
contact would be used in a Normally Closed loop.

> The various posts here appear to have
> confirmed my thoughts on this. As far as I
> know, electronics catalogs have always
> described a n.o. relay as the state of the
> contacts with no voltage applied...

That's correct.  Also, some manufacturers, such as Ademco, describe their
magnetic contacts as "Form 'A'" or "Form 'C'".  Form "A" means there's a
common lead and a N.O. lead.  When the magnet moves away the circuit opens.
Form "C" is another way of saying "SPDC".  There's a Common, a Normally Open
and a Normally Closed lead.  These can be wired for "cross and break" or
used in either type of circuit.

--

Regards,
Robert L Bass

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