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Re: Tutorials

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Sun, 4 Nov 2001 20:42:42 -0000
Message-ID: <1004906388.28075.0.nnrp-14.9e984b29@news.demon.co.uk>

Presumably you don't try to store those
values in the database though. It would be a modelling error to do so. The fact
that a hardware device has to report an
error condition through a special value
doesn't mean that a database used to
hold the data should do the same.

--
Jonathan Lewis
http://www.jlcomp.demon.co.uk

Host to The Co-Operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

Author of:
Practical Oracle 8i: Building Efficient Databases

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Murray Peterson wrote in message ...

>"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote in
>news:1004898834.23939.0.nnrp-14.9e984b29_at_news.demon.co.uk:
>
>> What is SCADA, and what devices is it using
>> to measure to 38 digits of precision ?
>>
>
>Supervisory Control and Data Acquisition
>
>The devices don't measure to that precision, but many of them use the
>extreme ranges of the values to indicate error conditions with the analog
>to digital conversion process (e.g. 1.0e-1022 indicates a low calibration
>voltage, 1.0e-1021 indicates a high calibration voltage, 1.0e+1023
>indicates power failure, etc.).
>
>Another issue arises with 32-bit counters -- the device reports in IEEE
>format, but an IEEE float cannot represent a 32-bit integer without error,
>so an IEEE double is required.
>
>--
>Murray Peterson
>Email: murray_peterson_at_shaw.ca (remove underscore)
>URL: http://members.shaw.ca/murraypeterson/
Received on Sun Nov 04 2001 - 14:42:42 CST

Original text of this message

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