Calculating The Current Position In Machine Coordinates - YASKAWA SGD7S-1R9D Product Manual

6.8.6

Calculating the Current Position in Machine Coordinates

When you reset the absolute encoder, the reset position becomes the reference position.
The host controller reads the coordinate Ps from the origin of the encoder coordinate system. The host
controller must record the value of coordinate Ps.
This section describes the reference position in the machine coordinate system.
The method to calculate the coordinate value of the present position from the origin of the machine
coordinate system is given below.
Machine coordinate
Value of
multiturn data
The current position P
P = P - P
M E S
×
P = M R + P
E
×
P = M R + P
S S
Symbol
P
Position data for the current position of the absolute encoder
E
M Current position of the multiturn data of the absolute encoder
P
Position of the current position within one rotation
O
P
Position data of the absolute encoder when absolute encoder was reset
S
M
Multiturn data of the absolute encoder when absolute encoder was reset
S
P '
Position of the absolute encoder within one rotation when absolute encoder was reset
S
P
Current position in machine coordinate system
M
R Pulses output per encoder rotation (value after dividing; setting of Pn212)
Note: The following formulas apply in Reverse Rotation Mode (Pn000 = n.1).
P = P - P
M E
= -M × R + P
P
E
× R + P
P = M
S S
1. If you are using a Rotary Servomotor, you must reset the absolute encoder. Refer to the fol-
Information
2. You can set the origin to a different position from the reset position. Refer to the following sec-
Origin (reference position)
-1 0
-1 ±0
P
S
in the machine coordinate system is calculated as follows:
M
O
'
S
S
O
'
S
lowing section for information on resetting the absolute encoder.
5.15 Resetting the Absolute Encoder
tion for information on the origin position offset.
5.16
Setting the Origin of the Absolute Encoder

6.8.6 Calculating the Current Position in Machine Coordinates

Current position
+1 +2
+1
M × R P
O
P
E
P
M
Meaning
on page 5-49
on page 5-52
6.8 Absolute Encoders
+3
+2
6
6-35