Corrected from:
- i700 servo inverter V01.05.06.9665
Response of the new version:
The consideration of existing delay times has been optimised for the touch probe function. Now, there occurs hardly any speed-proportional offset of the detected TP position:
The TP position offset in negative direction occurring so far has been eliminated by a corresponding consideration of the delay times of the actual position detection.
Hardware-dependent dead times of TP inputs DI1 and DI2 are now already considered at the firmware end (delay time less half the fluctuation range, different values for rising and falling TP edges).
As before, the dead time compensation function is available to compensate for delay times of the connected TP sensors, parameters 0x2DD0.1 (TP1) and 0x2DD0.2 (TP2).
The dead time compensation for TP2 works correctly now.
What happens?
Touch probe TP1 and TP2:
The detected TP position deviates proportionally to the speed from the actual mechanical position.
This is due to the inevitable internal delay times of the TP inputs and the actual position detection. The internally effective dead time of the actual position detection (approx. 250 µs) leads to an offset of the detected TP positions towards lower values that is proportional to the current speed. I.e. the position offset acts opposite to the actually expected direction. A delay time of the connected TP sensor itself would lead to an offset towards bigger positions.
Only TP2:
The delay time for the dead time compensation of TP2 selected under the parameter 0x2DD0.2 (TP2) is erroneously considered inflated by factor 2.
When does this behaviour occur?
The behaviour always occurs when using the touch-probe function with both possible touch-probe sources of the i700 servo inverter:
TP sensor (mark sensor, initiator) at digital input terminal (DI1, DI2)
Zero pulse of feedback system, e.g. during homing
Which products are affected?
- i700 servo inverter ≤ V01.04.00.9125
Short-term measures:
None or using TP sensors with a delay time of at least 250 µs. In this case, the internal delay times and the delay times of the TP sensor would compensate each other. For this, the delay times for the TP compensation under the parameters 0x2DD0.1 (TP1) and 0x2DD0.2 (TP2) would have to remain set to 0.000 µs.
Evaluation/recommendations:
Strictly speaking, the adaptation of the delay times considered inside the device means an incompatibility towards older firmware versions. The advantages of a more precise TP detection for future applications were decisive for the decision to accept the possible effects of the changed timing on some existing applications.
The i700 servo inverter is still in the initial phase of market introduction and therefore the number of TP function applications will still be at a manageable level.
