Siemens SIMOVERT MASTERDRIVES Manual page 805

05.2006
Resolution with
optical sin/cos
encoder
Entering the actual
value weighting
factor (AVWF)
NOTE
Siemens AG 6SE7087-6QX70 (Version AG)
SIMOVERT MASTERDRIVES
With optical sin/cos encoder ERN1387, the resolution of the measuring
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system is 2 = 16 777 216 steps per motor revolution: after "pulse
quadrupling" (evaluation of zero crossings), each 2048 sine and cosine
periods per revolution produce a "digital rough resolution" of 8196 steps
per motor revolution. The analog fine amplitude evaluation of the
sine/cosine signals resolves each quarter period with a further 2048
steps. If you want to use the full resolution of the ERN encoder for the
positioning and synchronization functions, you must set P171 = 24,
which reduces the resolution of the rotor position signal KK090 from 2
to the actually implemented resolution of 2
setting and set the actual value weighting factor (AVWF) LU = 1
encoder increment, you can only achieve traversing ranges (with linear
axes) or axis cycle lengths (with rotary axes) of 59.6 encoder
revolutions, as the position setpoints and actual values can otherwise no
longer be represented by the numeric range from -999 999 999 ... +999
999 999 LU (numeric range 999 999 999 LU / 16 777 216 LU per
revolution → 59.6 revolutions). For larger traversing distances, you must
therefore reduce the resolution "artificially" by setting P171 to values
< 24 or by selecting a smaller AVWFactor (i.e. a larger length unit LU).
Commissioning step:
Enter the actual value weighting factor (AVWF) (P169/P170 or
P152/P153):
For the actual value weighting factor (AVWF), you must enter the
number of length units per actual position increment (LU/increment) in
parameter P169/P170 if you use the position sensing system [330] for
the motor encoder in slot C, or in P152/P153, if you use an external
machine encoder [335].
♦ You must always enter 8 decimal places in the AVWF in P169 or
P153, padding any non-significant decimal places with "0" (e.g.:
AVWF = 1.5 LU/increments => P169 = 1. P170 = 5000000;
P170 = 5 would result in an incorrect AVWF of 1.00000005 !!)
♦ Please check carefully whether the AVWF has been entered
correctly. Many of the parameter and machine data settings
described below refer to the length unit LU and must be entered
again if the actual value weighting factor (AVWF) is changed.
It is normally recommended to use a length with three decimal places
for the LU, e.g. 1 LU = 0.001 mm = 1 µm or 1 LU = 0.001°. This is
particularly important if you use the SIMATIC S7 "Motion Control
Configuring Package" software /1/, in which the OP screens always use
3 decimal places for length parameters.
Compendium Motion Control
Technology Option F01
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. However, if you use this
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