The Command Position is the requested position (specified by the Command Value) with bounds checking applied. If the requested position is outside the Retract or Extand Limit, the Command Position will be set to the value of the limit, and the axis will go only to the limit. The Command Position is updated when any move command, or Set Parameters (P) command is issued using the Command parameter.
Why Bother?
If the Command Position is not the same as the requested position then one of two things has happened:
A program error has asked the axis to go to an invalid position. In this case the program error should be corrected. The PARAMETER ERROR bit in the Status word will be ON when this occurs.
The Command Value field has just been changed and the Motion Controller has not had a chance to acknowledge the new request. Note that the In Position bit is no longer valid for the rest of the scan. The In Position bit is valid only when the Command Value is equal to the Command Position.
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