Re: Tutorials

From: Murray Peterson <mwp_at_home.com.invalid>
Date: Sun, 04 Nov 2001 18:43:06 GMT
Message-ID: <Xns914F77BC43955farkle@24.71.223.45>

"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 - 12:43:06 CST