Eliminated from:
9400 HighLine SW V7.0
Behaviour of the new version?
If the limit values in system block LS_Limiter (C2708/x, C2709/x, C2710/x, requested via bits 3 to 6 of control word LIM_dwControl) are activated with positioning profiles, the parameterised acceleration is maintained and the drive decelerates to the limited speed before the target position is approached.
What happens?
The profile generator does not decelerate to the limited speed; instead, it continues travelling until the target is reached. The resulting deceleration is smaller than the parameterised deceleration. Due to the smaller deceleration the safety module may be triggered because the parameterised speed for the 'Safely limited speed' is exceeded.
Which products are affected?
9400 HighLine SW ≤ V5.1
9400 StateLine all firmware versions
When does the problem occur?
The problem occurs if a positioning motion is made using the LS_Positioner with the LS_Limiter and if the distance to the target position almost corresponds to the calculated braking distance. In addition, the S-ramp time must be greater than 0 s.
Possible diagnostics?
The oscilloscope can be used to record the profile speed (Pos_dnProfileSpeed_s). Use this variable to find out if the set speed is maintained.
Short-term measures/recommendations?
Instead of using the limit values in the system block LS_Limiter, use the override functions on system block LS_Positioner (POS_bEnableOverride = TRUE, POS_dnSpeedOverride_n and POS_dnAccOverride_n).
Evaluation:
The desired target position is still reached in spite of the functional restriction described here. However, certain basic conditions yield a slower deceleration than expected, which results in a higher speed that may even exceed the "safely limited speed". This can then trigger the safety module.
The required functionality can be achieved by proceeding as described under Short-term measures/recommendations.
Published with Service Message No. 38/2009
