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2 Analog I/O Modules
PTC Thermistor (Threshold)
This section describes details on PTC thermistor (threshold).
The value is stored in Data according to the resistance of the PTC thermistor and the values of Min. and Max..
The relationship between the resistance of the PTC thermistor, the values of Min. and Max., and Data is as follows.
PTC thermistor resistance (Ω)
10,000
Max.
Min.
100
Value stored in Data : 1
Value stored in Data : 2
Value stored in Data : 4
For the operation when the resistance of the PTC thermistor matches the value of Min. or Max., see "Hysteresis"
below.
Hysteresis
The system has a hysteresis of ±20 Ω for Min. and Max. that are set. For example, if Min. is set to 1,500 and Max. is
set to 7,000, the operation is shown as follows.
Value stored in Data
4
D
2
1
A : The value of Data changes from 1 to 2 when the resistance of the PTC thermistor is greater than or equal to
1,520Ω.
B : The value of Data changes from 2 to 4 when the resistance of the PTC thermistor exceeds 7,020Ω.
C : The value of Data changes from 4 to 2 when the resistance of the PTC thermistor is less than or equal to 6,980Ω.
D : The value of Data changes from 2 to 1 when the resistance of the PTC thermistor is less than 1,480Ω.
When setting Min. and Max., ensure that the difference between the two values is 41 or greater. If the
difference between the Min. and Max. is less than or equal to 40, Status 3 (Parameter setting error) is
stored in Status.
Behavior of the Status
If the resistance of the PTC thermistor is out of range, the following values are stored in Status.
If the resistance of the PTC thermistor is less than 100 Ω, status 6 (Wiring fault (out of minimum range error)) is
stored in Status.
If the resistance of the PTC thermistor is greater than 10,000 Ω, status 5 (Wiring fault (out of maximum range error))
is stored in Status.
2-22
Min. > PTC thermistor resistance
Min.
PTC thermistor resistance Max.
Max. < PTC thermistor resistance
1480
1520
6980
C
A
1500
7000
MICRO/I Hardware Manual
4
Value stored in Data
2
1
Time
7020
B
PTC thermistor resistance (Ω)
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