Accsense
VersaLog Data Loggers User’s Manual
Page 29
double
rtst;
double
tindex;
int
loop = 0;
tindex = (TMAX - TMIN) / 4;
t = (TMAX + TMIN) / 2;
rtst = T2R(t);
while
(0.999999999 * r > rtst || rtst > 1.000000001 * r)
{
if
(rtst < r) t += tindex;
if
(rtst > r) t -= tindex;
tindex /= 2;
rtst = T2R(t);
//call helping function for resistance in OHM
//make sure no infinite loop if the value is out of the range
if
(loop++ > 40)
break
;
}
return
t;
//always return value in degree C
}
//helping function
double
T2R(
double
t)
{
double
r;
// if t < 0
if
(t < 0)
r = R0 * (1 + A * t + B *
Math
.Pow(t, 2) + C * (t - 100) *
Math
.Pow(t, 3));
// if t >= 0
else
r = R0 * (1 + A * t + B *
Math
.Pow(t, 2));
return
r;
}
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Built-In Equations
Equation and Channel Type are two essential parameters to make sure the physical
measurement can be converted correctly.
An equation is a software functionality identified by its name of up to 16 characters. A built-in
equation is an equation provided by VersaLog SiteView software to convert a measurement for
a specific channel type.
A channel must have an equation assigned to it in order to make the measurement conversion.
“Digit” built-in equation can be assigned to any channel type. If you assign “Digit” equation to
a channel the physical measurement will be the original digital value measured by ADC
(Analog-to-digital converter) hardware.