2 Analog I/O Modules
2-22
MICRO/I Hardware Manual
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.
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.
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.
Value stored in
Data
: 1
Min.
> PTC thermistor resistance
Value stored in
Data
: 2
Min.
PTC thermistor resistance
Max.
Value stored in
Data
: 4
Max.
< PTC thermistor resistance
Value stored in
Data
4
2
1
PTC thermistor resistance (Ω)
10,000
Max.
Min.
100
Time
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.
B
A
D
C
1500 7000
1480
1520
6980
7020
Value stored in
Data
1
2
4
PTC thermistor resistance (Ω)
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
.
