Siemens SINAMICS S120, Function Manual

Page: 377 / 1094

Basic functions
7.20 Tolerant encoder monitoring
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
377
7.20.7 Pulse number correction for faults
Interference currents or other EMC faults can falsify encoder evaluation. However, it is
possible to correct the measured signals using the zero marks.
Commissioning
1. Set p0437.2 = 1 to activate "Pulse number correction for faults".
2. Define the permissible tolerance (encoder pulses) for the zero mark distance (p4680).
3. Define the limits of the tolerance window, up to which the drive corrects the pulse number
(p4681, p4682).
4. Using p4686, define the minimum zero mark length.
Sequence
1. This function completely corrects encoder pulse errors up to the tolerance window
(p4681, p4682) between two zero marks. The rate of correction is ¼ encoder pulses per
current controller cycle. As a consequence, it is possible to continually compensate for
missing encoder pulses (for example, if the encoder disk is dirty). Using the two
parameters, set the tolerance for the deviating pulse number.
If the deviation exceeds the tolerance window size, fault F3x131
1)
is output.
Note
When the "Commutation with zero mark" function (p0404.15 = 1) is activated, then the
system waits until fine synchronization has been completed before making a correction
(r1992.8 = 1).
The pole position for the commutation is also corrected. To do this, you do not have to
activate pole position adaptation (p0430.22 = 1).
This function does not make any corrections in the speed sensing.
2. Using p4686, set the minimum zero mark length. With a factory setting of 1, it is
prevented that EMC faults result in a zero mark error.
Shorter zero marks are only suppressed when "Zero mark edge detection" is
parameterized (p0437.1 = 1).
3. Zero mark deviations of less than the minimum zero mark length (p4686) are not
corrected.
4. A permanently failed zero mark is indicated using the fault F3x101 "Encoder x: Zero mark
failed"
1)
or the alarm A3x401
1)
"Alarm threshold zero mark failed".
1)
x = encoder number (x = 1, 2 or 3)