YASKAWA SGD7S series, Product Manual, Page: 279 / 629

6.12 Absolute Encoders
6.12.6 Calculating the Current Position in Machine Coordinates
6
Application Function
s
6-81
6.12.6 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.
The current position P
M
in the machine coordinate system is calculated as follows:
P
M
= P
E
- P
S
P
E
= M
×
R + P
O
P
S
= M
S
×
R + P
S
’
Symbol Meaning
Setting or Unit
Encoder Divided Pulse
Output (PAO and PBO)
Signals
Absolute Encoder
Position Output (PSO)
Signal
P
E
Position data for the current position of the
absolute encoder
Encoder output pulses
(encoder pulses x setting
of Pn212)
Encoder pulses
M
Current position of the multiturn data of the
absolute encoder
− −
P
O
Position of the current position within one rotation
Encoder output pulses
(encoder pulses x setting
of Pn212)
Encoder pulses
P
S
Position data of the absolute encoder when
absolute encoder was reset
M
S
Multiturn data of the absolute encoder when
absolute encoder was reset
− −
P
S
’
Position of the absolute encoder within one
rotation when absolute encoder was reset
Encoder output pulses
(encoder pulses x setting
of Pn212)
Encoder pulses
P
M
Current position in machine coordinate system
R Number of encoder pulses per revolution
Setting of Pn212 Encoder resolution
Calculations for Reverse Rotation Mode (Pn000 = n.

1)
PM = PE - PS
PE = -M × R + PO
PS = MS × R + PS PM = PE - PS
PE = -M × R - PO
PS = MS × R - PS’
If you are using a Rotary Servomotor, you must reset the absolute encoder. Refer to the following
section for information on resetting the absolute encoder.
5.17
Resetting the Absolute Encoder
on page 5-51
Machine coordinate
Value of
multiturn data
-1 0 +1 +2 + 3
-1
±0
+1 +2
Origin (reference po s ition) Current po s ition
M × R
P
E
P
O
P
S
P
M
Information