Establishing The Origin Using An Absolute Encoder - Omron CJ1W-NC271 - 12-2009 Operation Manual

Absolute Encoder Origin
8-6-6

Establishing the Origin Using an Absolute Encoder

G5-series/G-series Servo
Drives
Servo Drive Power Supply Input
CONNECT Bit (word n+1, bit 00)
Connection Status Flag (word n+16, bit 15)
Present Position Preset (word a, bit 08)
Positioning Completed (word b, bit 05)
No Origin Flag (word b, bit 06)
Busy Flag (word b, bit 13)
Feedback Present Position (words b+6, b+7)
Command Present Position (words b+8, b+9)
The present position data will be read from the
Servo Drive and the origin will be established when
CONNECTION Bit is set and the MECHATROLINK
is in communications status (the Connection Status
Flag is ON).
n = Beginning word of Common Operating Memory Area: n = 1500 + (unit number × 25)
b = Beginning word of Axis Operating Input Memory Areas specified in Common Parameters + (Axis No. −1) × 25
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• To use a motor with absolute encoders with the OMNUC G series and G5
series Servo Drives, use the motor as described below when setting the
absolute PG origin offset using origin search.
• If the limit input in the origin search direction is ON when executing the
origin search, origin search does not operate normally.
Start the origin search after moving the position where the limit input
in the origin search direction does not turn ON by jogging.
• If the origin search is started when the limit input is ON in the origin
search direction, an error terminates when the origin search operation
is completed (data setting error, error code: 3099).
The Position Control Unit establishes the origin by reading the absolute value
data saved in the absolute encoder using the following timing.
The zero point position offset that is set as a Servo parameter is added to the
absolute value data that is read and input to the Axis Operating Input Memory
Areas as the present position of the Position Control Unit.
In the following sections, the present position is given as the sum of the travel
distances for the operations for each axis.
Turning ON the Servo Drive
When the control power supply is turned ON, the G5-series Servo Drive or G-
series Servo Drive reads the absolute value data of the Servomotor with the
absolute encoder to the Servo Drive. When MECHATROLINK communica-
tions start (i.e., when a connection is established), the Position Control Unit
updates the present position using the absolute value data read from the
Servo Drive.
Absolute
value data
Absolute
value data
The origin will not be established (the No Origin Flag
will be ON) and the present position will become
invalid data when CONNECTION Bit is set and
MECHATROLINK communications are stopped (the
Connection Status Flag is OFF).
Position data
Preset data
invalid
Position data
Preset data
invalid
Section 8-6
Preset data
(See note.)
Preset data
(See note.)
Note: Once the Present Position
Preset has been executed,
the preset data will be read
when the connection is
established until the absolute
value data is read again.