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21. CUSTOM CURVE LINEARIZATION
Curve.exe
is a DOS-based, executable PC program used to set up an Extended meter so that
the readings have a user-defined, non-linear relationship with the input signal. The calculated
linearizing parameters are downloaded into non-volatile memory of the meter. For example, it
allows a meter to correct for transducer nonlinearity or to display volume of an irregularly shaped
tank based on liquid level. The curve-fitting
algorithm uses quadratic segments of varying
length and curvature, and provides dia-
gnostics to estimate curve fitting errors. The
program is self-prompting, avoiding the need
for a detailed printed manual. This manual
section is only intended as an introduction and
get-started guide.
PREREQUISITES
1)
PC-compatible computer with an available RS232 or USB port.
2)
Extended meter.
3)
An RS232 or USB board in the meter. This board
can be removed following meter setup.
4)
An RJ11-to-DB9 RS232 cable or a USB cable
to connect the meter to the PC (see Section 1,
Ordering Guide).
5) Curve.exe
software (downloadable from the web
at no charge).
GETTING STARTED
Download
curve.exe
into the same directory that will contain your data files, such as
c:\curves
.
Set the meter baud rate to 9600. To do so, press the
key to get to
SEr 1
, then set the
entry to
__
050
. Set the meter address to 1. To do so, press the
key to get to
SEr 2
, then
set the entry to
_
0011
. To execute the program from Windows, simply double-click on
curve.exe
, which is an executable file. Follow the steps on computer screens, which will
prompt you and provide extensive information. Pressing
R
(Enter) returns to the main menu.
You will be given the choice to enter your data in one of four modes:
1) Text file entry mode,
with an X value in one column and a Y value in another. There can
be additional columns, which are ignored. The file must have a DOS name of up to 8
characters and the extension .RAW. There can be from 5 to 180 rows. X is the input value
and should be in the unit of measure for which the meter was set up, such as mV, V, mA
or A. Y is the desired corresponding reading and can range from -99999 to 99999 with
any decimal point.
2) 2-coordinate keyboard entry mode,
where an actual X input signal is applied, and the
desired Y reading is entered from the keyboard.
3) 2-coordinate file entry mode,
where an actual X input signal is applied, and the desired
Y reading is provided from a file.
