YASKAWA SVC - Page 360

5.2 Absolute Encoders
5.2.2 Absolute Encoder System Startup
5-19
5
Machine-Specic Motion Control
Setting the Origin of the Machine Coordinate System
After the absolute encoder is initialized, the reference position to operate the machine with the
MP3000 must be set.
The origin of the absolute encoder and the origin of the machine coordinate system will not
match, so they must be corrected. The reference for the origin of the machine coordinate sys-
tem is the origin of the absolute encoder. The deviation from the origin of the absolute encoder
is the correction value (offset), and this establishes the origin position of the machine coordi-
nate system.
Each machine axis moves to the reference position for operation, and that position is the origin
in the machine coordinate system.
The negative of the value of IL
 16 (APOS) is written to OL  48 (OL  48 = -
IL
 16).
If the zero point of the machine coordinate system is set, the MP3000 will recognize the current
position when the power supply is next turned ON, as shown in the next section 5.2.5 Reading
Position Data When the Power Supply Is Turned ON. The zero point will not need to be set
again.
Current Value in the Machine Coordinate System
If an absolute encoder is used, the MP3000 calculates the axis position (i.e., the current posi-
tion in the machine coordinate system) as follows when the power supply is turned ON.
Current position in machine coordinate system (IL
 10 or IL  16) = Position when the
Servo power supply is turned ON + Value of OL
 48 setting parameter (Zero Point Position
Offset in Machine Coordinate System)
When encoder position X is set as the origin of the machine coordinate system (0),
OL
48 is set to -X.
When IL
10 is 10,000 and OL48 is 100, the negative value of the position when
the Servo power supply is turned ON is as follows:
OL48 - IL10 = 100 - 10000 = -9900
You can set this value of -9,900 in OL
48 to set the current position in the machine coor-
dinate system as the machine coordinate origin.
1. Use IL
10 to make the machine coordinate reference position the reference, or use
IL
16 to make the current position in the machine coordinate system the reference.
2. The position when the servo power supply is turned ON is the value that is calculated with the
following formula and then converted to reference units:
Multiturn data × Number of encoder pulses + Initial incremental pulses (position within one
rotation)
Refer to your SERVOPACK manual for details on initial incremental pulses (position within one
rotation).
Example
Origin of machine
coordinate system
Encoder position (X)
Machine coordinate
OL  48
Origin of the absolute encoder
Encoder coordinate
Example
Important