BECKHOFF KL3201 - Manual (Page 10)

Functional description
8 KL3201, KL3202 and KL3204
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 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
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 = a
1
* Y_R 2 + b
1
* Y_R + c
1
(1.2)
or
Y_T = Y_R if output in Ω (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
RL
RTD
RL
1sec
X_R
Y_R
Y_T
1:1
1:1
1:1
Y_THS
Y_TAS
1:1 1:1
ammount rep.
active
add. bits
(Siemens format)
Y_AUS
A_w,B_w
A_h,B_h
Siemens output
format
Linearisation
a1,b1,c1
A_a,B_a
ADC
Offset,Gain-parameter
Manufacturer
scaling
user scaling