Panasonic FP E Series, User Manual

Page: 44 / 440

2-16
2.5.2 Loading of Thermister Temperature Data
Reading the value of the FP
Σ
special data resister enables to load the analog value data that
corresponds to the resistance value of the thermister.
Applicable special data register
Symbol Thermister No. Special data register Digital value after conversion
V0 Thermister 0 DT90040
V1 Thermister 1 DT90041
K0 to K1000
Thermister measuring temperature – A/D conversion table (example: 3450K)
•
Work out the temperature and the thermister resistance value from the temperature characteristic table
of the used thermister.
•
The converted digital values can be calculated by the formula described in the previous page.
Temperature (
°
C)
Thermister resistance
(k
Ω
)
Converted digital
value
Resolution (
°
C)
50 4.3560 332 0.135
60 3.1470 409 0.130
70 2.3170 487 0.128
80 1.7340 561 0.135
90 1.3180 628 0.149
100 1.0170 688 0.167
110 0.7940 740 0.192
120 0.6277 785 0.222
130 0.5017 822 0.270
140 0.4052 853 0.323
150 0.3305 878 0.400
Note) (Total precision of AD converter in which microcomputer is built: ±5LSB)+(Precision of thermister)
is not included in the above digital values.
Conversion program using scaling instruction (F282)
•
Appropriate data which interpolated from nonlinear data can be obtained by creating converted digital
values and temperature data as a data table and executing the scaling instruction (F282).
DT90040: Special data register
(Digital value after thermister input conversion)
DT0: Beginning of data table
DT100: Converted data (temperature)
Example of data table creation
Input data
(Converted digital value)
Output data
(Temperature
DT0 11
DT1 332 DT12 50
DT2 409 DT13 60
DT3 487 DT14 70
• • • •
• • • •
DT11 878 DT22 150
Note) Specify (the number of data to be paird) + 1 for DT0.