Omron CS1W-MC221 - 02-2008 Operation Manual page 494

Overview
Origin Search in
Automatic/Manual Mode
9-1-2 Using Absolute Encoders
Absolute Encoder Setup
1,2,3...
!Caution When using an absolute encoder with a G-series Servo Driver, stop the axis
Determine the search method according to the mode of each task, as shown
below.
Method
Forced Origin Bit
Present Position IOWR instruction
Preset
G54
Origin Search Origin Search Bit
G28
Teaching Box
The absolute encoder retains absolute data by using the backup battery when
the MC Unit or Servo Driver is turned OFF. When the MC Unit is turned ON
again, if the system is set to the servo-lock state, absolute data will be read
from the absolute encoder to determine the present position. No origin search
is required. The absolute encoder setup procedure is briefly described below.
Refer to 9-2 Input Signals Required for an Origin Search to 9-4 Origin Search
Operations for details.
Absolute encoder data must be reset and the absolute origin must be set at
the MC Unit in the following cases.
• When a Servomotor incorporating an absolute encoder is connected for
the first time or replaced.
• When the battery is replaced.
• When the retained absolute data is lost because the encoder cable is
removed for a long time.
Use the following procedure to set up the absolute encoder.
1. Connect the motor to the machine.
2. Referring to the Servo Driver operation manual, connect a new battery.
3. Referring to the Servo Driver operation manual, set the retained absolute
data to zero. At this point, the origin data of the absolute encoder is differ-
ent from the origin of the machine.
4. Execute servo-lock with the MC Unit. The present value of the absolute en-
coder is read by the MC Unit.
5. Perform an origin search to move the Servomotor to the origin.
6. Turn the absolute encoder OFF and ON in order to save the present value
as the origin. The absolute encoder value corresponding to the workpiece
origin is set as absolute data.
With servo-lock in effect, the present value is automatically set to the read
value less the absolute origin set value. Therefore, no origin search is
required. Refer to 9-6 Setting the Origin With an Absolute Encoder.
before locking the servo. Position error will occur if the servo is locked while
the axis is moving.
Section 9-1
Manual Mode Automatic Mode
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Possible in Teaching Box Enabled Mode
or in Teaching Box Priority Mode regard-
less of whether the MC Unit is in Manual
or Automatic Mode.
467