User Manual

70
Shifting Input Values Section 4-1
Method for a 2-point
Shift
Use a 2-point input shift if you want to increase the accuracy of the readout
values across the range of the sensor.
1,2,3... 1. Shift the Controller readout at two points, near room temperature and near
the value at which the temperature of the control target is to be controlled.
For this reason, check the control target temperature (B) and Controller
readout (A) with the control object temperature near room temperature and
near the set point.
2. Then use the following formulas to calculate the upper-limit and lower-limit
temperature input shift values based on the readout temperatures and de-
sired temperatures.
The shift is illustrated in Figure 3.
Figure 3 Illustration of 2-Point Shift
a. Lower-limit temperature input shift value
b. Upper-limit temperature input shift value
3. After setting the calculated values to insl and insh, check the Controller
readout (A) and control target temperature (B).
4. Here, offsets are set at two points, near room temperature and near the set
point. To improve accuracy within the measurement temperature range,
another point in the measurement temperature range other than the set
point should be set instead of room temperature.
Example of a 2-point
Temperature Input
Shift
In this example, we use the ES1B K 140 to 260°C specification. In equations 1
and 2, the set temperature lower limit YL is 0
°C and the set temperature upper
limit YH is 260
°C. Check the temperature of the control target.
The temperature input offset values can be calculated as shown below when
the Controller readout Y1 is 40
°C for a room temperature X1 of 25°C and
when the Controller readout Y2 is 105
°C for a set point temperature X2 of
110
°C.
Lower-limit Temperature Input Shift Value
0
Controller readout (A)
Set temperature upper
limit YH (e.g., 260°C)
Controller readout after
shifting (e.g., 110°C)
Controller readout before
shifting (e.g., 105°C)
Controller readout before
shifting (e.g., 40°C)
Controller readout after
shifting (e.g., 25°C)
After shifting
Upper-limit temperature
input shift value insh
Before shifting
X1 Room temper-
ature (e.g., 25°C)
Control target temperature (B)
Lower-limit
temperature input
shift value insl
Set temperature lower
limit YL (e.g., 0°C)
X2 Near set point (e.g., 110°C)
insl =
YL − Y1
Y2 − Y1
× {(X2 − Y2) − (X1 − Y1)} + (X1 − Y1)
insh =
YH − Y1
Y2 − Y1
× {(X2 − Y2) − (X1 − Y1)} + (X1 − Y1)
C
insl
-27.3
Lower-limit
temperature
input shift
value
insl =
0 − 40
105 − 40
× {(110 − 105) − (25 − 40)} + (25 − 40) = −27.3 (°C)