CPU Types
FPΣ User's Manual
32
Suitable thermistor types
Any thermistor with a resistance in the range of 200Ω to 75kΩ can be used.
Manufacturer Thermistor type (B constant) Measurement range guide
3390K -50–100°C
3450K 50–150°C
4300K 100–220°C
Shibaura Electronics
5133K 150–300°C
NOTE
• Make sure the length of the cable between the FPΣ CPU and the thermistor
is less than 10m.
• The length of the lead wire is 150mm. Use a thin electrical wire (AWG28) if
you want to make it longer. Connect and bundle the wire without any stress.
• If the conversion value does not remain stable, we recommend adding an
external capacitor or the like.
3.5.1 Loading Thermistor Temperature Data
You can load the analog data corresponding to the thermistor resistance by reading in the
FPΣ’s special data register. To access special data registers and special internal relays, use
the PLC-independent system variables.
Applicable special data registers
Thermistor Special data register System variable Converted digital value
V0
DT90040 sys_iPotiInputV0
V1
DT90041 sys_iPotiInputV1
0–1000
Thermistor Measurement Temperature - A/D Conversion Table (Example with 3450K)
Calculate the relationship between temperature and thermistor resistance using a table with
the temperature characteristics of your thermistor.
Use the conversion formula to calculate the post-conversion digital value.
Temperature [°C]
Thermistor resistance [kΩ]
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
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