Notes On The Number Of Controllable Drives; Number Of Drives Depending On The Control Mode And Cycle Times - Siemens Sinamics S120 Comissioning Manual

A.4.5

Notes on the number of controllable drives

A.4.5.1

Number of drives depending on the control mode and cycle times

The number of axes that can be operated with a Control Unit depends on the cycle times
and the control mode. The number of usable axes and the associated cycle times for each
control type are listed below. The other available remaining computation times are available
for options (e.g. DCC).
Cycle times for servo control
This following table lists the number of axes that can be operated with a Control Unit in the
servo control mode. The number of axes is also dependent on the cycle times of the
controller:
Table A- 3 Sampling time setting for servo control
Cycle times [µs]
Current con- Speed controller
troller
125 125
62.5 62.5
31.25 31.251
1)
At the cycle level 31.25 µs, you can also create the following objects:
1)
Sensor Module External (SME) and SMC20 that support the current firmware and hardware. These can be recognized
from the Article end number ... 3.
No additional axis can be operated in this cycle level.
Adjustable pulse frequencies and current controller cycles for servo control
The pulse frequencies that can be set depending on the selected current controller cycle are
shown in r0114. Because of the integrating current measurement, pulse frequencies that are
a multiple of half the current controller sampling frequency should be preferred. Otherwise,
the current is not measured synchronous to the pulse frequency and a fluctuating actual
current value results. This causes disturbance in the control circuits and higher losses in the
motor (such as pulse frequency 5.333 kHz and current controller cycle 62.5 μs).
Commissioning with Startdrive
Commissioning Manual, (IH3), 07/2016, 6SL3097-4AA10-0BP0
Number
Axes
6
3
1
)
A.4 System rules, sampling times and DRIVE-CLiQ wiring
Motor/dir. measur-
ing systems
Infeed
1 [250 μs]
1 [250 μs]
1 [250 μs]
TM
1)
6 / 6 3 [2000 μs]
3 / 3 3 [2000 μs]
1 / 1 3 [2000 μs]
Appendix
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