Functioning IP/IE3202
The IP3202-Bxxx or IE3202 analog input module allows four resistance sensors to be connected directly. The resistance sensors can be connected according to the 2, 3 or 4 wire connection method. Calculation and linearisation of the resistance value to obtain a temperature is performed by a microcontroller in the module.
Temperatures are output in 1/10 °C (1 digit = 0.1 °C). In addition to this, a broken wire or short circuit is reported to the slave or to the controller, and indicated by the error LED.
PT100, NI100, PT200, PT500, NI120, NI1000 and PT1000 elements are implemented over their full measuring ranges as resistance sensors. The module can be fully configured over a fieldbus. A self-defined scaling of the output can, for instance, be performed, or the temperature conversion can be switched off. In the latter case, the measurement is output is in the range from 10 ohm up to 1.2/5.0 kohm with a resolution of 1/10 resp. 1/2 ohm (the internal resolution of the resistance value is 1/255 ohm).
Process data output format
|
Process data (hex) |
Process data Decimal (Integer) |
Measured value |
|---|---|---|
|
0xF63C |
-2500 |
-250°C |
|
0xF830 |
-2000 |
-200°C |
|
0xFC18 |
-1000 |
-100°C |
|
0xFFFF |
-1 |
-0.1°C |
|
0x0000 |
0 |
0.0°C |
|
0x0001 |
1 |
0.1°C |
|
0x03E8 |
1000 |
100°C |
|
0x07D0 |
2000 |
200°C |
|
0x1388 |
5000 |
500°C |
|
0x2134 |
8500 |
850°C |
Process data
The process data that is transmitted to the K-Bus is calculated from the following equations:
X_RL: ADC value of the supply cables
X_RTD: ADC value of the temperature sensor, including one supply
cable
X_R: ADC value of the temperature sensor
A_a, B_a: Manufacturer, gain and offset compensation (R17,
R18)
A_h, B_h: Manufacturer scaling
A_w, B_w: User scaling
Y_R: Temperature sensor resistance value
Y_T: Measured temperature in 1/16 °C
Y_THS: Temperature after manufacturer scaling (1/10 °C )
Y_TAS: Temperature after user scaling
Y_AUS: Process data to PLC controller
a) Calculation of the resistance value:
X_R = X_RTD-X_RL (1.0) Y_R = A_a * (X_R -B_a) (1.1)
b) Curve linearisation:
Y_T = a1 * Y_R^2 + b1* Y_R + c1 (1.2) or Y_T = Y_R if the output is
in ohms (1.3)
c) Neither user nor manufacturer scaling are active:
Y_AUS = Y_T (1.4)
d) Manufacturer scaling active (factory setting):
Y_THS = A_h * Y_T + B_h (1.5) Y_AUS = Y_THS
e) User scaling active:
Y_TAS = A_w * Y_T + B_w (1.6) Y_AUS = Y_TAS
f) Manufacturer and user scaling active: (1.7)
Y_1 = A_h * Y_T + B_h Y_2 = A_w * Y_1 + B_w Y_AUS = Y_2
Conceptual circuit diagram
