Yaskawa JAPMC-MC2300 - Manual (Page 274)

10.1 Absolute Position Detection Function
10.1.3 Finite Length/Infinite Length Axes and Absolute Position Detection
10-3
10
Absolute Position Detection
This way the absolute machine position can be detected and automatic operation can begin immediately after power is
turned ON with an automatic position detection system.
Terminology: Absolute Data
Absolute data that is stored in an absolute encoder has two types of data: the absolute reference position (initial incremental
pulses; PO) and the number of rotations (multi-turn data; N) from the absolute reference position.
The absolute reference position is the phase-C position when the absolute encoder is initialized and is the reference position for
absolute-position detection.
Only the number of rotations (N) can be cleared when the absolute encoder is initialized, and the initial incremental pulses will
not change.
Information: Calculation of Absolute Position
We can determine the absolute position (P) using the following data.
Data stored in an absolute encoder
• Absolute reference position (initial incremental pulses): PO
• Number of rotations from the absolute reference position (multi-turn data): N
Parameter determined according to the number of bits of servomotor
• Feedback pulses per motor rotation: RP
Equation to calculate the absolute position
• Absolute position (P) = N × RP + PO
10.1.3 Finite Length/Infinite Length Axes and Absolute Position Detection
There are two types of axes. An infinite length axis resets the current position to a specified value every rotation, and
the finite length axis does not.
Set a finite length axis if return and other operations are performed only within a specified range or for an axis that
moves in one direction only without resetting the position every rotation.
Set an infinite length axis for conveyor belts and other operations that require the position to be reset every rotation.
There are two types of position control available with an infinite length axis. Simple Absolute Infinite Length Position
Control and Infinite Length Position Control without Simple Absolute Positions.
An absolute encoder performs absolute position detection with a finite or infinite length axis depending on the Axis
Selection (fixed parameter 1, bit 0) of the Machine Controller.
Set the Machine Controller fixed parameters and SERVOPACK parameters to select the absolute position detection
function with an absolute encoder. The setting procedures are different for finite and infinite length axes. Refer to
10.2.1 System Startup Flowchart on page 10-4 for details.