Eliminated from:
9400 HighLine SW V7.0
Behaviour of the new version?
Previously, if the maximum traversing speed was dynamically modified during the acceleration phase of a positioning profile so that the actual traversing speed was reduced (e. g. with a corresponding change-over of the speed override via
POS_dnSpeedOverride_n), the new traversing speed would be reached (actual acceleration decreased and new negative acceleration built up) using the parameterised
deceleration/S-ramp time.
In the new firmware version, the actual acceleration is decreased using the parameters for the acceleration phase (
acceleration and S-ramp time) and the deceleration built up via the parameterised deceleration/S-ramp time. Compared to older firmware versions with identically set profile parameters this can result in slightly shorter or longer positioning times.
Which products are affected?
9400 HighLine SW ≤ V5.1
What happens?
If the override function of the LS_Positioner is used to reduce the speed of an active profile, the deceleration is slower than it is set in the 'Deceleration' parameter. The outcome of this is that the speed value, which is supposed to be reached by means of the override value, can only be reached too late or not at all.
When does the problem occur?
The problem occurs if the speed is reduced by means of the override function during the acceleration phase of a positioning profile in such a way that the target will have to be approached immediately (braking distance). Causes could be:
- Change-over of the speed override via POS_dnSpeedOverride_n
- Positioning sets with a final speed <> 0
- 'Hard' profile change at speeds <> 0
The deceleration value of the profile also needs to be lower than the acceleration value and the S-ramp times must be set to values > 0[s].
Possible diagnostics?
The behaviour can be identified if, under the conditions described, a positioning process takes longer than expected to complete. In such cases, an oscillograph can be used to record the traversing speed (system variable POS_dnProfileSpeed_s) and the cursor function used to measure the deceleration ramp in order to calculate the deceleration that is currently active. If this value does not match the parameterised deceleration, the behaviour described here has occurred.
Short-term measures/recommendations?
Empirical adaptation of the deceleration values in the positioning set, until the required positioning profile is achieved.
Evaluation:
In spite of the described function restriction, the desired target position is reached at any rate. However, the described basic conditions yield a smaller deceleration than parameterised.
Published with Service Message No. 38/2009
