Siemens SINAMICS S120, Function Manual

Page: 374 / 1094

Basic functions
7.20 Tolerant encoder monitoring
Drive functions
374
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
7.20.3 Freezing the speed raw value
If, for high speed changes, the dn/dt monitoring function responds, then the "freeze speed
raw value" function gives you the opportunity of briefly specifying the actual speed value
therefore equalizing the speed change.
Commissioning
1. Set parameter p0437.6 = 1 to activate the "freeze speed raw value" function.
Sequence
1. If the dn/dt monitor responds, the alarm A3x418 " Encoder x: Speed difference per
sampling rate exceeded"
1)
is output.
2. A frozen actual speed value limited to just two current controller cycles is supplied.
3. The rotor position continues to integrate
4. The actual value is released again after two current controller cycles
1)
x = encoder number (x = 1, 2 or 3)
7.20.4 Adjustable hardware filter
The adjustable hardware filter function allows an encoder signal to be filtered, therefore
suppressing short interference pulses.
Commissioning
1. Set parameter p0438 ≠ 0 to activate the "adjustable hardware filter" function.
Parameterization
1. In parameter p0438 (square-wave encoder filter time) enter the filter time in the range
from 0 to 100 μs. The hardware filter only supports values 0 (no filtering), 0.04 μs,
0.64 μs, 2.56 μs, 10.24 μs and 20.48 μs
If a value is set that does not match one of the discrete values specified above, the
firmware automatically sets the next closest discrete value. The drive does not output an
alarm or fault message.
2. You can see the active, effective filter time in parameter r0452.
Note
The zero mark alarms F3x100, F3x101 and F3x131
1)
, that are already output for a zero
mark with a width of ¼ encoder pulse at half n_max speed, are suppressed when the
hardware filter is activated.
1)
x = encoder number (x = 1, 2 or 3)