Flintec LDU 69.1 - Manual (Page 19)

LDU 69.1 Technisches Handbuch, Rev. 12 January 2011 Page 19 of 28
8.4. Filter Setting Commands – FL, UR
A digital filter can be set which will eliminate most of the unwanted disturbances. The command FL is used to
define the digital filter settings, the command UR is used to define an averaging of up to 172 measurement
values. Please note that these filters are positioned immediately after the A/D Converter and therefore affect all
aspects of the weighing operation.
8.4.1. FL Filter Settings
This command defines the filter cut off frequency and the filter characteristics.
The digital IIR filter operates as 2 nd order low pass filter and Gauss-, Bessel- or Butterworth characteristics.
The attentuation is 40dB/decade (12 dB/octave).
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
FL
 F+00003 Request: FL = 3
FL 1
 OK Setup: FL = 1
WP  OK Setup saved
The permitted settings are from 0 to 17 (see table below ).
Factory default setting: 3 (Butterworth 2 Hz).
Setup of IIR filter
Cut-off frequency 0.2 Hz 0.5 Hz 1 Hz 1.5 Hz 2 Hz 3 Hz
Gauss
17 14 11 8 5 2
Bessel 16 13 10 7 4 1
Butterworth 15 12 9 6 3 0
Filter characteristics:
 Gauss: delayed step response (no overswing, minimum group delay)
 Bessel: normal step repsonse (no overswing, linear phase)
 Butterworth: step response with overshoot (small overswing, linear frequency)
8.4.2. UR Averaging and Update Rate
For LDU 69.1 following averaging is adjustable:
UR 0 1 2 3 4 5 6 7
Values / second 172 86 43 21 10 5 2,5 1,3
Check / setup of the averaging:
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
UR
 U+0000 Request: 172 values / second
UR 2  OK Setup: 43 values / second
WP  OK Setup saved
Factory default is 0 (no averaging; data output rate = 172 values / second)