Beckhoff KL301 Series, Документация

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Product overview
KL301x, KL302x 11 Version: 4.1
2.4 Basic function principles
The analog input terminals
KL3011 and KL3012 process signals in the range from 0 mA to 20 mA
KL3021 and KL3022 process signals in the range from 4 mA to 20 mA
with 12-bit resolution (4095 steps). The terminal inputs are differential inputs with common ground. Due to
the differential inputs, the terminals are particularly suitable for ground-free measurements in current loops.
Cross-currents caused by voltage differences at the input terminals do not lead to any appreciable
measurement distortion up to a difference in potential of 35 V (U
CM
= 35 V).
The LEDs indicate the operating state of the associated terminal channels.
• green Run LED:
◦ 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 Error LED:
◦ On: The limit stop of the A/D converter has been reached. The current is greater than 21.5 mA.
◦ Off: Normal operation
Process data output format
In the delivery state the process data are shown in two's complement form (integer -1 corresponds to
0xFFFF). Other presentation types can be selected via the feature register (
R32) [ } 38] (e.g. signed amount
representation, Siemens output format).
Measured value Output
KL3011, KL3012 KL3021, KL3022 dec hex
0 mA 4 mA 0 0x0000
10 mA 12 mA 16383 0x3FFF
20 mA 20 mA 32767 0x7FFF
Calculation of process data
The terminal continuously takes measured values and stores the raw values of its A/D converter in register
R0 [
}
36] (RAM ). The calculation of the correction with the calibration values takes place after each
sampling of the analog signal. This is followed by manufacturer and user scaling:
The process data that are transferred to the Bus Coupler are calculated using the following equations:
Y_a = (B_a + X_adc) * A_a
Y_aus = Y_a (1.0) Neither user nor manufacturer scaling is active.
Y_1 = B_h + A_h * Y_a
Y_aus = Y_1 (1.1) Manufacturer scaling active: (Default setting)
Y_2 = B_w + A_w * Y_a
Y_aus = Y_2 (1.2) User scaling active
Y_1 = B_h + A_h * Y_a
Y_2 = B_w + A_w * Y_1
Y_aus = Y_2 (1.3)
(1.4) Manufacturer and user scaling active
Key
Name Name Register
X_adc Output value of the A/D converter -
Y_aus Process data for controller -
B_a Vendor calibration: Offset
R17 [ } 37]
A_a Vendor calibration: Gain
R18 [
}
37]
B_h Manufacturer scaling: Offset
R19 [ } 37]
A_h Manufacturer scaling: Gain
R20 [
}
37]
B_w User scaling: Offset
R33 [ } 38]
A_w User scaling: Gain
R34 [ } 38]