Basic function principles

Process data output format

In the delivery state, the measured value is displayed in increments of 1/10 °C in two's complement format (integer). The complete measuring range is output for each resistance sensor. Other presentation types can be selected via the feature register (e.g., signed amount representation, Siemens output format).

Measured value

Hexadecimal output

Signed integer output

-250.0 °C

0xF63C

-2500

-200.0 °C

0xF830

-2000

-100.0 °C

0xFC18

-1000

-0.1 °C

0xFFFF

-1

0.0 °C

0x0000

0

0.1 °C

0x0001

1

100.0 °C

0x03E8

1000

200.0 °C

0x07D0

2000

500.0 °C

0x1388

5000

850.0 °C

0x2134

8500

Resistance limit values

R > 400 Ω: Bits 1 and 6 (overrange and error bits) in the status byte are set. The linearization of the characteristic curve is continued with the coefficients of the upper range limit up to the limit stop of the A/D converter (approx. 500 Ω for PT100).
R<18 Ω: Bits 0 and 6 (underrange and error bits) in the status byte are set. The smallest negative number is displayed (0x8001 corresponds to -32767).
For overrange or underrange the red error LED is switched on.

LED display

The LEDs indicate the operating state of the associated terminal channels.

Red LEDs: ERROR

  • On: Short circuit or wire breakage. The resistance value is in the invalid range of the characteristic curve.
  • Off: The resistance is in the valid range of the characteristic curve.

Calculation of process data

The process data that are transferred to the terminal bus are calculated using the following equations:

X_RL:

 

ADC value of the supply line

X_RTD:

 

ADC value of the temperature sensor, including one supply line

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

X_R = X_RTD-X_RL
Y_R = A_a * (X_R - B_a)

(1.0)
(1.1)

Calculating the resistance value

Y_T = a1 * Y_R2 + b1* Y_R + c1
Y_T = Y_R if output in Ω

(1.2)
(1.3)

Linearization of the characteristic curve

Y_AUS = Y_T

(1.4)

Neither user nor manufacturer scaling is active

Y_THS = A_h * Y_T + B_h
Y_AUS = Y_THS

(1.5)

Manufacturer scaling active (factory setting)

Y_TAS = A_w * Y_T + B_w
Y_AUS = Y_TAS

(1.6)

User scaling active

Y_1 = A_h * Y_T + B_h
Y_2 = A_w * Y_1 + B_w
Y_AUS = Y_2

(1.7)

Manufacturer and user scaling active

Basic function principles 1:
KL3224x - Data flow