Sensor adjustment
To simplify the correction of sensors for zero-point and if necessary also for
gain, the MEASURED VALUE function includes a special function which per-
forms this adjustment automatically (see also Section 6.2.2).
7.5 Scaling, decimal point setting
To display the electrical signal of a sensor as measured value in its physical si-
ze, it is nearly always necessary to perform decimal point shift, zero-point cor-
rection, and multiplication with a factor. To perform these steps the functions
EXPONENT ´
EX
´, BASIS ´
BA
´, and FACTOR ´
FA
´ are provided. For a detailed
description of scaling, with an example, please refer to the Manual, Section
6.3.11.
Displayed value
= (corrected measured value - BASIS) x FACTOR.
Decimal point setting
First of all the position of the decimal point should be checked and if necessary
adapted, using the EXPONENT function, to the desired resolution and to the
units appropriate to the sensor. Using the EXPONENT function ´EX´ the deci-
mal point can be shifted as far to the left (-) or to the right (+) as the display and
printer permit.
Function EXPONENT
´
EX
´
Select by key:
FUNKTION...
Enter as per Sec. 5.4
1: 3
EX
Example:
Force transducer with output 2.0000 V should indicate 1000.0 N.
The decimal point must be shifted three positions to the right by me-
ans of exponent 3. From the new actual values 0.0 N and 2000.0 N
it is now easy to calculate the necessary factor 0.5. The base value
will probably only be needed for the purposes of zero-point correct.
BASE VALUE function
´
BA
´
Select by key:
FUNCTION
... Enter as per Sec. 5.4
1: 0 0 1.2
BA
FACTOR
function
´
FA
´
Select by key:
FUNCTION
... Enter as per Sec. 5.4
1:0.5 0 0 0
FA
Once the scaling values have been programmed and the measured value thus
duly modified, the ´
CORR
´ arrow appears in the display.
The scaling values can also be specified automatically by means of
two-point adjustment. First of all, in the MEASURED VALUE functi-
on, the measured value is set to its zero state (icy water, unpressuri-
zed, etc.) (see Sections 6.2.1/2) and then, with a defined value, the
setpoint (boiling water) is entered (see Section 6.2.3).
ALMEMO
®
8390-2
37
Sensor programming
