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6 Motion Control Programming
6-14
NJ-series CPU Unit Motion Control User’s Manual (W507)
6-5 Positions
This section describes the positions that are used in motion control programming.
The MC Function Modules uses the following two types of positions.
The following figure shows the relationship between the command position and the actual position.
The command position and actual position share the following items.
* If there is any following error before the change, the following error value is maintained in the actual position.
The following table lists the valid positions for each axis type.
*1 For a virtual servo axis, the actual position is the same as the command position. (However, there is some-
times calculation error because processing is performed with long reals in the MC Function Module.)
*2 This is used when there is no actual encoder.
6-5-1 Types of Positions
Type of position Definition
Command position This is the position that the MC Function Module outputs to control an axis.
Actual position The actual position as input from the Servo Drive or encoder input.
Item Command position Actual position
Count Mode You can set Linear Mode or Rotary
Mode. The same Count Mode is used as
for the command position.
Position increment You can set one of the following:
mm,
µ
m, nm, inch, degree, or pulse.
The unit is the same as the unit of
the command position.
Software limits You can set the range of operation
of the software. The range is the same as the range
for the command position.
Changing the current position You can change the actual position
to any desired position. This value will be set to the same
position as the command position.
*
Defining home Home is either defined or
undefined. The status of home is the same as
the command position.
6-5-2 Valid Positions for Each Axis Type
Axis type
Types of positions
Command position Actual position
Servo axis Applicable Applicable
Virtual servo axis Applicable
Applicable
*1
Encoder axis Cannot be used. Applicable
Virtual encoder axis Cannot be used.
Applicable
*2
Servo Drive
Feedback
counter
Command
position
counter
Electronic
gear
In-position check
Electronic
gear
MC Function Module
Motion
control
instruction
User program
M
E
Motion
control
processing
Command
position
(command units)
Actual position
(command units)
Command position
(pulses)
Actual position
(pulses)
Following
error
counter
Position loop
Velocity loop
Current loop
Remainder
Remainder