|
|
|
42213 Sarah Way, Temecula, CA 92590,
USA |
Tel: 800-854-8530 (USA)
Tel: 951-699-2437
Fax: 951-695-7246
sales@electronumerics.com |
 |
Micro Series Custom Curve Linearization
Panel Meters & Counters
Easy Programming for
Custom Nonlinear Curve Fits
Applicable to Micro
Process, Strain Gauge, Load Cell Meters,
Frequency / Rate Meters, Totalizers
Features
-
Achieves exceptional
accuracy with low-cost transducers.
-
Extends transducer
operating range on high and low ends.
-
Solves application
problems involving non-linear relationships.
- Available with Extended versions
of Micro digital panel meters, counters and timers.
- Easy setup by entering data
points into a computer spreadsheet, or typing in desired readings for
actual signal inputs.
-
Exceptional
accuracy from 0.1% to 0.01% of full scale with few data points, made
possible by curvilinear spline fits.
|
Description
Custom curve linearization is
a feature available with the Extended option version of all Micro
digital panel meters, counters and timers, excluding only temperature
meters. The latter already include preset linearization for specific
temperature sensors.
Custom curve linearization
can provide exceptional accuracy from low cost transducers, provided
that these are repeatable. It can extend the working range of
transducers on the high and low ends. It can also solve special
application problems where there is a non-linear relationship between
the input and the desired readout.
Linearizing is implemented
for Micros in the form of 20 nonlinear spline-fit segments, which provide much better accuracy than a
larger number of straight line segments. The typical error will be from
0.1% to 0.01% of full scale, depending on the number of data points used for setup, the
error in the data points, and the severity of non-linearities or
discontinuities.
Easy Setup
Setup of a
Micro Linearizing Process Meter requires an external PC, which is
connected to the meter via an RS-232 cable, and utilizes linearizing software
furnished by Electro-Numerics. To download, go to our
Downloads Page. A Micro serial communications
board is required, but can be removed following setup. Three meter programming
methods are offered:
Spreadsheet Method: Data points consisting of the input signal in Volts or Amps and
the desired reading are entered into an Excel spreadsheet or into a text
text file using a space, comma or tab as the delimiter. There can be from
2 to 240 data points. Our software then calculates 20 spline-fit
segments and downloads their coefficients into the meter.
Actual
Input Method:
The meter is hooked up to the actual signal source, and
the user enters the desired readings for different signal levels. There can be from
2 to 240 input / reading combinations. Our software then calculates 20
spline-fit segments and downloads their coefficients into the meter.
This method automatically compensates for any errors in the transducer.
Polynomial
Method:
The mathematical formula relating the
input to the output is entered into the computer, which then uses this
data to calculate the spline-fit segments. This method is ideal if the
mathematical relationship is knows, for example to calculate the
contents of a tank based on the known geometry of the tank.
|
|
Applications
The ability to apply custom
curve linearization opens many possibilities, including the following:
-
Altimeters, since
the relationship between pressure and altitude is very non-linear.
-
Rate of ascent
based on successive altimeter readings.
-
Square root extraction
from differential pressure transducers, whose signal may have zero
offset.
-
Volume of
irregularly-shaped tanks, such as horizontal cylinders, based on
measured liquid level or liquid pressure at the base of the tank.
-
Non-linear transducers,
such as thermistors or CdS cells.
-
Fine-calibration of linear
transducers, since even nominally linear transducers will have
nonlinear components.
-
Extending the working
range of transducers, since many transducers become nonlinear at
the low and high ends.
-
Compensating for
inaccuracy of low-cost transducers.
|
 |
 |
| Measuring
tank volume The Extended Micro process meter can display the volume of
irregularly shaped tanks based on measured tank level or static pressure
at the base of the tank. A common example is a cylindrical tank lying on
its side. The tank can further be tilted to facilitate drainage, as
illustrated. Spherical tanks or spheroidal water tanks are another
example.
|
Rate from
successive readings The Extended process meter allows the display of rate based on successive
readings, for instance flow rate based on changes in liquid level or static pressure in a
tank. In the above illustration, the
meter displays the rate in gallons at which a horizontal tank is being emptied. The input
to the meter can be nonlinear, since only the linearized readings are compared for the
determination of rate.
|
Micro & Mighty Series Downloads
|
.gif){kind=small}