Siemens SIMATIC FM 353 Manual page 273

Effect: PWM
The motor phase current can be changed between 0 % and 100 %. Current modifi-
cation is possible at zero speed and during continuous travel. On acceleration/de-
celeration, the current is always 100 % (max).
f
pulse
PWM
I
PWM
100 %
MD50
MD51
Effect: Boost
During acceleration/deceleration, the activated boost signal triggers a current in-
crease on the drive unit. The amount of the increase is set on the drive unit. At
zero speed and during continuous travel, the current is always 100 %.
f
pulse
I
Boost
100 %
Optional signal "Current-sourcing zero" or "Zero pulse external"
To support stepper motor axis synchronization, the FM 353 processes a cyclic in-
put signal (which is dependent on the axis movement) as a zero marker (see Sec-
tion 4.4). This signal can be either the "Current-sourcing pattern zero" signal from
the stepper drive, or a "Zero pulse external" signal (e.g. initiator) generated once
per stepper motor revolution. The active level of the signal can be parameterized.
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0
Description of Functions
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9-73