Basic information about the drive system
13.12 System rules, sampling times and DRIVE-CLiQ wiring
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
1033
Note
When the current controller sampling time is set, the speed controller sampling time is
automatically preset:
Servo control: Speed controller sampling time = current controller sampling time
Vector control: Speed controller sampling time = current controller sampling time x 4
The preassignment of the speed controller sampling time can be changed to influence T
mapc
.
For example, the current controller sampling time can be increas
ed from 800 µs to 1000 µs
mapc
can be set to be a multiple of 1000 µs.
Asynchronous node on the isochronous PROFIBUS
For cycle mix, lengthened base cycles with the following effects often result on the
isochronous PROFIBUS:
● Because the isochronous PROFIBUS can no longer be operated with the default setting,
adaptations must be made to the hardware configuration.
● The increased setting values for T
i
, T
o
and T
dp
have disadvantageous effects on the
dynamics of the position control loop.
Despite a cycle mix, the parameter p2049 can be used to operate the axis with the different
current controller sampling time asynchronously on the isochronous PROFIBUS. This allows
the default setting of the hardware configuration to be retained.
This, however, causes the advantages of the isochronous operation for the asynchronous
axis to be lost:
● The setpoints act at times that differ from T
o
, i.e. an interpolating position-controlled
operation with other axes is not possible.
● The actual values are read at times that differ from T
i
, i.e. the actual values must not be
used to control other axes.
A critical application would be, for example, a spindle that cuts a thread with the
programmed thread pitch together with a position-controlled Z-axis by the controller
adjusting the plunging depth of the Z-axis depending on the spindle position.
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