Yaskawa MP930 - Manual (Page 234)

7.1 Structure of the Absolute Position Detection Function
7 -3
Absolute Data
Absolute data that is stored in an absolute encoder is comprised of the number of rotations (P)
from the absolute reference position and position (PO) in a one Servomotor rotation. This abso-
lute data is read as serial data when the machine is turned ON.
All other operations are the same as that for ordinary incremental encoders.
In other words, we can determine the absolute position PO from the equation for absolute value
(P) which is absolute value (P) = N ¢ RP + PO if we use the following:
D Number of rotations from the absolute reference position: N
D Number of pulses per one Servomotor rotation: RP
D Position in one Servomotor rotation: PO
Holding Absolute Data
An absolute encoder uses a battery to maintain absolute data at all times even though power
is turned OFF. It also updates data if there is a change.
The battery is connected to the battery terminal of the Servopack.
Yaskawa supplies the battery module (JRMSP-120XC9600) on which the following battery is
mounted.
D Type of battery: Lithium
D Battery configuration: ER6VC3, 3.6 V ¢ 1
D Non-conducting service life: About 1 year
Reading Absolute Data
When power is turned ON, absolute data is read to the Servopack as well as to the MP930 where
it is used to automatically calculate the absolute position and set the machine coordinate sys-
tem. This way the absolute machine position can be detected and automatic operation can be-
gin immediately after power is turned ON. 7