Which products are affected?
LenzeMotionControlV0304.lib (part of the Positioner software package V3.4)
The problem occurs in the L_MCProfileGenerator function block.
What happens?
If the profile is changed while the jerk reduction function is activated (C3500/x > 0) an acceleration step occurs.
When does the problem occur?
The following conditions must be complied with at the same time so that the behaviour occurs:
• The following profile is generated with jerk reduction (C3500/x > 0) and
• an active profile calculation is changed over by starting a following profile. As a result, a new profile calculation is started.
This overchange may occur for instance in case of the following scenarios:
- A new profile is passed on explicitly to the profile generator out of the user program.
- Touch probe positioning with a residual distance > 0.
- In case of homing with an offset to be traversed. However, this only applies if the Template Positioner is used since here the homing movement is determined by the profile generator. If the library function blocks are used L_REF is usually used for homing purposes.
Usually the deceleration is reduced in such a way that the speed and the deceleration are zero when the target position is reached. If a profile is changed over it may happen that the speed is zero but the deceleration is still unequal zero (e. g. if the jerk time of the new profile is larger than in the previous one). As a result, a reversing (change of sign with regard to the speed) occurs. If in addition the new target position is very close (distance < than the current profile parameter 'acceleration' under C3400/x * tjerk²) a deceleration step occurs, i.e. the deceleration is reduced linear under consideration of the jerk time.
The faulty behaviour is caused by the L_MCProfileGenerator profile generator, i. e. it may appear in the Template Positioner and in programs using this function block.
The error only occurs when the wSProfileMode = 1 (C3037 = 1) is set.
Possible diagnostics?
Recording the speed setpoint and actual speed value by means of the Global Drive Oscilloscope.
Short-term measures/recommendations?
If the jerk reduction function for the following profile is deactivated (jerk time = 0) an acceleration step does not occur.
Evaluation:
It is very improbable that the conditions mentioned before occur at the same time. The acceleration/deceleration difference is very small. Due to the slow traversing speed a slight cracking noise may be heard at the point of time when the error occurs. However, the target position is always reached. An uncontrolled movement does not occur.
