Save and Restore Actual Position Offset

KINGSTAR Configuration Tool allows you to save a drive's last actual position before disconnecting and powering it off, and restore that position the next time you reconnect to EtherCAT.

To achieve this, KINGSTAR provides the Save and Restore Actual Position Offset feature. This feature saves the offset between KINGSTAR's last actual position and the drive's last actual position, and restores the offset when reconnecting to EtherCAT.

The actual position offset is affected by the Unit Conversion configuration. The following formulas illustrate how KINGSTAR calculates the offset with and without the unit conversion enabled:

• Without Unit Conversion configured:
  

PositionOffset = KINGSTARMotionActualPosition - DriveActualPosition

• With Unit Conversion configured:

PositionOffset = KINGSTARMotionActualPosition - DriveActualPosition * (KINGSTARMotionUnitConversionDenominator / KINGSTARMotionUnitConversionNumerator) * KINGSTARMotionAxisDirection // -1 if reversed, otherwise 1

NOTE:  Extra encoder is not supported.

NOTE:  The position offset is saved together with the current unit conversion settings. If these settings are changed before the next EtherCAT connection, the saved offset will become invalid. To prevent incorrect positioning, please clear the offset before reconnecting.

Using the Save and Restore the Actual Position Offset Feature

Follow the steps below to enable and use the Save and Restore the Actual Position Offset feature in KINGSTAR Configuration Tool:

1. The feature is disabled by default, to enable it in KINGSTAR Configuration Tool:
   1. Open the KsTuning.exe.config configuration file, locate IsSaveAndRestorePositionOffsetEnabled and set its value to true. The configuration file is located at C:\Program Files\IntervalZero\KINGSTAR\bin\ksm64Tuning\KsTuning.exe.config
   
   
   2. Restart KINGSTAR Configuration Tool.
2. To enable the feature in the project, open KINGSTAR Configure Tool, navigate to the Connection Settings page, and select Save and restore position offsets in the Axis Settings section. This action displays the activation buttons for saving and restoring the position offsets for the selected axes (see Step 4) and enables axis settings to specify whether the feature is applied to each axis (see Step 3).
3. After selecting the Save and restore position offsets option in Step 2, you must apply the feature to the desired axes. Go to each axis's Configure page and select the Save and restore offsets option. This option is unselected by default. Only the selected axes' offsets can be saved or restored when activating this feature.
4. Now you can use the activation buttons (see Step 2) to save or restore the position offsets for the selected axes:

Activation buttons below the Save and restore position offsets option:

• If the selected axes are connected, you can click the Save offsets to file button to save the current position offsets of the axes to the Position Offset file. Otherwise, write the position offsets stored in the project file to the Position Offset file.
• Click the Load offsets from file button to load the position offsets into the project file. If the selected axes are currently connected, click this button will write the position offsets to the axes.

Activation buttons at the top of the Connection Settings page:

• Click the Save position offsets and disconnect button to save the position offsets of the selected axes to both the Position Offset file and the project file, and then disconnect the EtherCAT connection.
• Click the Connect and restore position offsets button to connect to the EtherCAT and restore the position offsets from the Position Offset file. If the Subsystem detects a mismatch between the offset values in the Position Offset file and the project file when clicking this button, a Data Conflict prompt will appear. You can choose either way to ensure data consistency:
  • Use the data in the position offsets file and replace the offsets in the project.
  • Use the offsets stored in the project and overwrite the position offsets file with them.