Allen-Bradley 2080-LC20-20QBB User Manual page 63

Rockwell Automation Publication 2080-UM005E-EN-E - March 2018
Analog input to thermistors
Thermistor 3
Thermistor 2
Thermistor 1
Thermistor 0
Note: Terminal block to wire
commons is not included in
Micro800 package.
The "+DC10" terminal supplies 10V DC power source to the Thermistor inputs (I-00 to I-03).
Calculate for Thermistor Resistance
While connecting Analog input to thermistor as shown in previous diagram,
calculate input voltage using the following equation:
R
i
V =
i
R + R
i t
To calculate for thermistor resistance, use the following equation:
R V - V R
i ref i i
R =
t
V
i
Where:
V = Voltage input (±5% without calibration; ±2% with calibration)
i
R = Resistance input (14.14 KΩ ±2%)
i
R = Thermistor resistance (10 KΩ Thermistor is recommended)
t
V = 10V ±0.5V
ref
Micro820 controllers support 10 KΩ type thermistors.
IMPORTANT
In order to get the best results, the system must be calibrated.
1 2 3 4
1 2 3 4
+DC10 I-00 I-02 COM0
1 2 3 4 5 6 7 8
-DC24 I-01 I-03 I-04
* V
ref
Wire Your Controller Chapter 4
46255
I-05 I-07 I-09 I-11
9 10 11 12 13 14 15 16
I-06 I-08 I-10 NU
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