Basic functions   
7.10 Direction reversal without changing the setpoint 
  Drive functions 
334  Function Manual, 11/2017, 6SL3097-4AB00-0BP5 
 
Uncontrollable acceleration of the drive with an external speed actual value 
When using an external speed actual value for the speed controller via p1440, positive 
feedback can occur in the speed control loop. As a consequence, the drive accelerates up 
to its speed limit and can be damaged. 
•  When using external speed actual values for the speed controller, additionally change 
its polarity when reversing the direction of rotation (p1821 = 1). 
 
Note 
Position reference is lost at direction reversal 
If direction reversal is configured in the da
ta set configurations (e.g. p1821[0] = 0 and 
p1821[1] = 1), when the function module "Basic positioner" or "Position control" is activated, 
the absolute adjustment is reset after each data set changeover (p2507), as the position 
reference is lost when the 
direction of rotation is switched over. 
Overview of the important parameters (see SINAMICS S120/S150 List Manual) 
 
  r0069[0...8] 
CO: Phase current actual value
 
  r0089[0...2] 
Phase voltage, actual value
 
  p1820[0...n] 
Reverse output phase sequence
 
  p1821[0...n] 
 
  p1959[0...n] 
Rotating measurement configuration
 
  p2507[0...n] 
Position control absolute encoder adjustment status