BECKHOFF KL3311 User Manual
Page 8
Functional description
6
KL3311, KL3312, KL3314 and KL3302
U
k
< U
kmin
: Bits 0 and 6 (under range and error bits) in the status byte are
set. The linearization of the characteristic curve is continued with the
coefficients of the lower range limit up to the limit stop of the A/D converter
or to the minimum value of 0x8000.
For over range or under range the red error LED is switched on.
LED display
The four LEDs indicate the operating state of the associated terminal
channels.
Green LEDs: RUN (not applicable for KL3314)
• On: normal operation
• Off: Watchdog-timer overflow has occurred. If no process data are
transmitted by the Bus Coupler for 100 ms, the green LEDs go out.
Red LEDs: ERROR
• On: Wire breakage. The resistance is in the invalid range of the
characteristic curve of the respective thermocouple.
• Off: The resistance is in the valid range of the characteristic curve.
Process data
The process data that are transferred to the terminal bus are calculated
using the following equations:
X_ref:
ADC value of the reference point
T
ref
:
Temperature of the reference point
U
ref
:
Voltage value of the reference point
X_R:
ADC value of the temperature sensor
U
m1
:
Voltage 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
U
k
:
Sum of U
ref
and U
m1
T:
Measured temperature in 1/16 °C
T
h
:
Temperature after manufacturer scaling (1/10 °C)
T
a
:
Temperature after user scaling
T_AUS:
Process data to PLC
a) Voltage value of the reference point:
T
ref
= A
00
*
X_
(1.0)
U
ref
= a
1
* T
ref
2
+ b
1
* T
ref
+ c
1
(1.1)
b) Measured temperature in 1/16°C:
U
m1
= A_a * X_m + B_a
(1.2)
U
k
= U
ref
+ U
m1
(1.3)
T = a
0
* U
k
2
+ b
0
* U
k
+ c
0
(1.4)
c) Neither user nor manufacturer scaling are active:
T_AUS
=
T
(1.5)
d) Manufacturer scaling active (factory setting):
T
h
= A_h * T + B_h
(1.6)
Y_AUS = T
h
e) User scaling active:
Ta = A_w * T + B_w
(1.7)
Y_AUS = T
a
f) Manufacturer and user scaling active:
(1.8)
Y_1 = A_h * T + B_h
Y_2 = A_w * Y_1 + B_w
Y_AUS = Y_2