Siemens SIMOVERT MASTERDRIVES Manual page 191

05.2006
Actual-value
weighting factor
Siemens AG 6SE7087-6QX70 (Version AG)
SIMOVERT MASTERDRIVES
AVWF = actual-value weighting factor as conversion constant/factor.
For example, if 1 LU = 1 µm, a decimal setpoint of 1000 LU represents
a travel distance of 1000 µm, or 1 mm.
Without the AVWF factor, the length information always refers to the
encoder pulses depending on the resolution of parameter P171 (motor
P171
encoder) 2 .
e.g. P171 = 12 → 4096 LU/revolution
The AVWF is calculated from this as follows:
Path distance
AVWF =
LU per
Roller
=
AVWF
LU per motor
The aim should be to have a resolution of about 1 µm / encoder
increment. Table 7-5 shows how large the factors are and hence how
high a resolution is to be selected.
In the example, the AVWF factors result from a roller diameter of
300.00 mm (circumference = 942477 µm). This must then be multiplied
by the gearbox factor (AVWF*).
P171 Resolution
12
13
14 16384
15 32768
16 65536
17 131072
18 262144
19 524288
20 1048576
21 2097152
Table 7-5 AVWF factors resulting from a roller diameter of 942477 µm
This results in an AVWF factor (which should be less than 1) of
0.71905288 or, as a fraction
Numerator 942477
=
Deno min ator 131072
as gearbox factor or factor for the AVWF.
More encoder increments per revolution should therefore be specified
(P171) than there are LUs per revolution.
Compendium Motion Control
per motor revolution
motor revolution
circumfere nce
×
revolution gearbox
AVWF
4096 230.096924
8192 115.048462
57.524231
28.7621155
14.3810577
7.19052887
3.59526443
1.79763222
0.89881611
0.44940805
=
. 0 71905288
0
Functions
or
factor (i)
AVWF*
23.0096924
11.5048462
5.7524231
2.87621155
1.43810577
0.719052887
0.359526443
0.179763222
0.089881611
0.044940805
7-25