8 Configuration
44
Example The temperature inside an oven is measured with a resistance thermometer and
displayed on a device. The reading on the device deviates from the actual temperature
as a result of the sensor temperature drifting. At 20°C the device reads 15°C, at 80°C
it shows 70°C (exaggerated example for better understanding).
Procedure h Determine lower measurement value (as low as possible and constant) with a refe-
rence measuring instrument;
Example: Oven temperature 20°C (= room temperature)
h Set start value at the device to this lower measurement value;
Example: Set start value (FtS) to 20
h Increase temperature and determine higher measurement value (as high as posible
and constant) with reference measuring instrument;
Example: Increase oven temperature to 80°C
h Set end value at the device to this higher measurement value;
Example: Set end value (FtE) to 80
Characteristic
curve
The following diagram shows the changes in the characteristic curve caused by the
fine adjustment (point of intersection with the x axis as well as ascent)
Reset
fine adjustment
In order to reset fine adjustment, the same value hast to be given to start value (FtS)
and end value (FtE) (e. g. set both parameters to 0). This automatically sets the start
value to 0 and the end value to 1 (factory setting).
A
Caution:
If start value and/or end value deviate from the factory-set values (FtS=0 and FtE=1), a
fine adjustment has already been done before. In this case the fine adjustment has to
be reset (see below).
Repeating fine adjustment without doing a reset before means that an already adju-
sted characteristic curve is used. This leads to wrong values.
20°C / 80°C
Oven
20°C / 80°C
15°C / 70°C
Display on the device
Actual temperature at
reference measuring instrument
(e. g. thermometer)
Sensor
20 80
20
80
70
15
Before fine
adjustment
After fine
adjustment
Measurement
(Reference)
Display
(Instrument)
Special case: Offset
If the deviation between measured value
and displayed value at the low and high
measuring point is identical, an offset cor-
rection is sufficient (ascent remains
unchanged). In this case, fine adjustment
is not required.
v Chapter 8.1 “Analog inputs “InP””
Parameter OFFS
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