Eliminated from:
9400 HighLine SW V7.0
Behaviour of the new version?
A change to the timing response when reading out the position value from the absolute value encoder on a cyclical basis means that the zero pulse signal is now assigned to the position value correctly. As a consequence, angular drift monitoring (C0621 <> 0) is rightly triggered with absolute value encoders connected at X8 if the actual position and the set position of the zero pulse signal differ.
Description of the problem
The drive sporadically indicates the error 'Encoder monitoring: pulse deviation detected' (C0168 (bits 0 to 25) = 8060990 = 0x0007b003e) in C0166.
When does the problem occur?
The problem only occurs if the following conditions are met too:
- An absolute value encoder is connected at X8.
- Angular drift monitoring has been activated (C0621 <> 0).
- The absolute value encoder is rotating at a speed of under 100[rpm].
When the zero pulse signal is detected, the position value is transmitted from the absolute value encoder again and compared with the absolute position read on the last zero pulse. The difference between the two most recently read position values must correspond to the number of encoder increments specified in C0420.
An unfavourable timing response, however, can lead to an offset between the zero pulse and the assigned position value and, as a result, to the monitoring function being triggered in error.
Which products are affected?
9400 HighLine SW ≤ V5.1
Diagnostics options?
The behaviour can be diagnosed if angular drift monitoring is triggered sporadically at speeds lower than 100[rpm] despite the parameters of the absolute value encoder (C0420, C0421, C0422, C0427) being set correctly and the feedback system being wired properly.
Short-term measures/recommendations?
Since angular drift monitoring is only active at speeds of under 100[rpm] anyway if absolute value encoders are connected, the monitoring function should be deactivated via C0621 = 0.
Evaluation:
This functional restriction is seen only rarely in practice, since several conditions must be met before it will arise. The angular drift monitoring function checks the zero pulse and absolute position value for plausibility; the functional restriction means that the user cannot employ this plausibility check. But since the check is already deactivated at the factory, this functional restriction will presumably affect very few applications.
Published with Service Message No. 38/2009
