C.4.5 Filter setting Commands – FM, FL, UR
Using the commands FM and FL, a digital filter type and strength can be set which will eliminate most of the
unwanted disturbances. Please note that these filters are positioned immediately after the A/D Converter
and therefore affect all aspects of the weighing operation.
FM
Filter Mode FIR / IIR
Choose filter mode, permitted values are “0” for IIR and “1” for FIR.
Master ( PC / PLC ) sends
DAS 72.1 responds
Result
FM
¿
M+00001
Request: FM = 1 (FIR)
FM_0
¿
OK
Setting: FM = 0 (IIR)
WP
¿
OK
Setting saved
The digital IIR filter works as a low-pass filter of 2nd order with Gaussian characteristic, damping is 40
dB/decade; see table mode 0.
The digital FIR filter works as a low-pass filter with quick response; damping see table mode 1.
Factory default: 0
FL
Setup filters
Command for setup cut off frequency, permitted values are 0 … 8.
Master ( PC / PLC ) sends
DAS 72.1 responds
Result
FL
¿
F+00003
Request: FL = 3
FL_1
¿
OK
Setting: FL = 1
WP
¿
OK
Setting saved
Filter values can be choosen between 0 and 8, see table below.
FL= 0 means no filter in mode 0 or 1 (command FM).
Factory default: 3
Mode 0 Characteristic (IIR-Filter)
FL
Settling time to 0.1%
(ms)
3dB Cut-off frequency
(Hz)
Damping @300Hz
(dB)
Output-rate
*
(samples/s)
0
no filtering
**
600
1
55
18
57
600
2
122
8
78
600
3
242
4
96
600
4
322
3
104
600
5
482
2
114
600
6
963
1
132
600
7
1923
0.5
149
600
8
3847
0.25
164
600
*
Output-rate = 600/2
UR
samples/s
** Antialiasing filter 17 Hz @ 60 dB/decade
Page 38
Manual DAS 72.1
