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56
System Functions
Section 3-3
At start-up the internal measured position of the MC Unit will be determined
by using the following formula.
As the relevant position for the application is the current position read by the
encoder relative to the origin point determined at setup, the following opera-
tion needs to be applied.
Absolute Encoder Setup
Procedure
Perform the setup operation for the absolute encoder in the following cases:
• When using the machine for the first time.
• When the backup alarm (A.81) is generated.
• When the Servo Driver’s power is turned OFF and the encoder cable is
removed.
The operation can be done by using the Parameter Unit, the front panel on
the Servo Driver, or using the personal computer monitoring software. Be
sure to follow the procedure carefully. Any mistakes in performing the proce-
dure may lead to faulty operation.
■
Absolute Encoder Setup
At the setup of the application the incremental position of the origin
needs
to be determined. Perform the following actions:
• Set the correct Servo Driver settings. When the Servo Driver is set up for
absolute encoder, the MC Unit position will be automatically updated.
• Put the Servomotor into the origin position for the system.
• Execute the Servo Driver absolute encoder setup function (Fn008) to
reset the multi-turn data. Note that performing this operation will stop
communication between Servo Driver and MC Unit.
• Power down the system and put the power back on. The MC Unit mea-
sured position of axis 0 has now been set and is equal to the
. The
measured position is represented by the MPOS axis parameter. The
value can be used in the start-up routine of the application.
Determining absolute
position
At every startup the measured position will be updated to the actual position
of the Servomotor. This position
is the position as read by the encoder and
will need to be compensated for the origin point position
. The application
initiation routine should contain the following steps.
• Define the current position relative to the origin point position. This possi-
ble by using the OFFPOS axis parameter or the DEFPOS command.
• During the parameter setting the UNITS axis parameter is used determin-
ing the unit conversion factor. The absolute position is modified accord-
ingly.
Note The coordinate system of the MC Unit is not synchronized to the coordinate
system of the Servo Driver. The user must verify that the range of the Servo-
motor position falls into the MC Unit range. If not, the position will be adjusted
within range and the position data is invalid.
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