6.10 Polarity Detection
6.10.1
Overview
If you use a Linear Servomotor that does not have a polarity sensor, then you must detect
the polarity.
Detecting the polarity means that the position of the electrical phase angle on the elec-
trical angle coordinates of the Servomotor is detected. The SERVOPACK cannot control
the Servomotor correctly unless it accurately knows the position of the electrical angle
coordinate of the Servomotor.
The execution timing and execution method for polarity detection depend on the encoder
specification as described in the following table.
Encoder Specifi-
cation
Polarity Detection Execution
Timing
Polarity Detection Execution
Method
Incremental
encoder
Each time the control power
supply to the SERVOPACK is
turned ON (Even after you exe-
cute polarity detection, the posi-
tion of the polarity will be lost the
next time the control power
supply to the SERVOPACK is
turned OFF.)
n
Use the Servo ON command
(Enable Operation com-
mand).
n
Use the polarity detection
function of the S.
n
Execute the Fn080 (Polarity
Detection) utility function
from the Digital Operator.
Absolute encoder Only for initial setup, or after the
SERVOPACK, linear encoder, or
Servomotor has been replaced
(The results of polarity detection
is stored in the absolute encoder,
so the polarity position is not lost
when the control power supply is
turned OFF.)
n
Use the polarity detection
function of the S.
n
Execute the Fn080 (Polarity
Detection) utility function
from the Digital Operator.
If you use a Linear Servomotor that does not have a polarity sensor, you
will not be able to turn ON the servo until polarity detection has been
completed.
6.10.2
Restrictions
The Servomotor will move when you execute polarity detection. The following conditions
must be met before you start.
n
It must be OK to move the Moving Coil about 10 mm. (If polarity detection fails, the
Moving Coil may move approximately 5 cm. The amount of movement depends on
conditions.)
n
The linear encoder pitch must be 100 μm or less. (We recommend a pitch of 40 μm or
less for an incremental encoder.)
n
As much as possible, the motor must not be subjected to an imbalanced external
force. (We recommend 5% or less of the rated force.)
n
The mass ratio must be 50x or less.
n
The axis must be horizontal.
n
There must be friction equivalent to a few percent of the rated force applied to the
guides. (Air sliders cannot be used.)
Assumed Conditions
Sigma-7 Series SERVOPACKs
Basic Functions That Require Setting before Operation
Polarity Detection > Restrictions
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