Corrected from:
- Inverter Drives 8400 TopLine V14.00.00
Response of the new version:
From the above-mentioned firmware version, linear encoders in which a position step change could lead to the described behaviour can be directly evaluated as position encoders (C422=6, 7, 8). In this way, the behaviour no longer occurs.
Which products are affected?
Inverter Drive 8400 TopLine up to firmware version 12.01.00.00
What happens?
An abrupt change of the position value of a position encoder is not directly output at LS_MutliEncoder.dnPosition_p. Depending on the change in value, the LS_MultiEncoder.nActSpeed_v angular difference output for a certain time shows a high speed value in the position.
When does the problem occur?
This behaviour is typical of linear SSI encoders with laser scanning in the case of a beam interruption.
The behaviour will usually not occur in the case of rotative position encoders.
Background:
The output signals dnPosition_p and nActSpeed_v of LS_MultiEncoder are generated by differentiation and a subsequent integration. This mechanism causes the behaviour.
Diagnostics options?
Recording of the LS_MutliEncoder.dnPosition_p and LS_MultiEncoder.nActSpeed_v signals if the position encoder executes an intended position step change.
Short-term measures/recommendations?
None. From the signals mentioned, no conclusions with regard to the actual position and movement of the machine part must be drawn when the behaviour occurs.
Evaluation:
The position step change at the position encoder usually only occurs in the event of an error (encoder error, measuring beam interruption, ...). SSI encoders typically indicate such an error with a status bit or an implausible position value (e.g. FFFFxh). This error is then detected in the inverter. Due to the behaviour, however, the position cannot be used again yet directly after eliminating the error status from the encoder. The required delay for transferring the position for purposes of homing or position control is not fixed and is not predictable. If the delay is not taken into consideration, an incorrect actual position is used in the inverter. The behaviour is only detected during commissioning if there is an error in the position encoder. This is coincidental.
