Command position, Target position, D.2 position status fields – Delta RMC101 User Manual
Page 864: D.2.1 command position, D.2.2 target position
RMC100 and RMCWin User Manual
D-2
Offset:
40,000
Position Range:
-25,535 to 40,000
Discussion:
Because Scale is negative, the positions range from Offset - 65,535 to Offset.
Example 5:
Scale:
-31,541
Offset:
-10,000
Position Range:
-65,536 to -10,000
Discussion:
Because Scale is negative, the positions range from Offset - 65,535 to Offset.
However, because the lower limit would be less than -65,536 (-75,536), it is truncated at -65,536.
Notice that positions greater than the Offset (-10,000) are not valid. They were beyond -65,535 and
therefore wrap around to -9999 to 0.
D.2 Position Status Fields
D.2.1 Command Position
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:
1. 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.
2. 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 Note that the In Position bit is no longer valid for the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.
D.2.2 Target Position
When the axis is in Closed Loop Mode, the Target Position is the calculated instantaneous ideal
position for the axis. The Target Position is calculated every loop by the target generator state
machine of the on-board motion control program. The PID routine uses the difference between
the Target Position and the Actual Position as its input to compute any required corrective drive.