Re: Caddx/Ademco Downloading

[Nomen Nescio <nobody@xxxxxxxxx>]

Al Mundy said:

>Well, IIRC, any modem that uses the hayes command set can be limited to
>a max connect speed.

That's not the problem.  The problem is that so-called Hayes-compatible
modems really aren't.  They communicate okay at standard speeds like 300,
1200, and 2400, but the Bell 103 spec calls fror the modem to communicate
at any desired speed between 0 and 300 baud.  The clone modem manufacturers
figured no one would want to run a modem at 75 baud, so they didn't
implement that feature.

As to why panel manufacturers don't include modem chips, the reason is
simple:  cost.  If you are selling panels for under $100, every part
counts, and the fewer components you use, the more money you make.  This
was particularly true when remotely programmable panels were first
introduced, and "high speed" modems would have been a massively expensive
feature to include.  So, the panel manufacturers used the panel's
microprocessor to do direct serial I/O, which meant their only cost was
firmware development:  no additional components required.  This
unfortunately imposes speed limitations, but at the time these panels were
first introduced, 1200 baud was considered fast.

Now, the manufacturers are faced with a  backwards compatibility problem.
If they built a panel that used a 56K modem to download, that modem would
be incapable of slowing down enough to program older panels.  Dealers would
have to have two modems.   They would bitch, and it would generate lots of
calls to tech support.  Plus, panels would cost a little more.

- badenov