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Sin/Cos - Encoder Connections
3.3.3 Sin/Cos Encoder
Interface X3A
The Sin/Cos encoder provides two differential analog channels for
incremental position and two differential analog channels for the absolute
position of the motor.
The analog cosine and sine wave signals of tracks A and B have a voltage
of 1 Vpp with an Offset of 2.5 V. This analog voltage is measured, and a
high-resolution position value is determined as a result. This high-resolution
position value is very important for good speed control of a gearless motor.
Tracks C and D give an absolute signal to the control unit. The period
corresponds exactly to one mechanical revolution of the encoder.
Therefore, it is absolutely necessary to ensure these signals are well
shielded! Noise on the analog signals resulting from breaks in the
shield or improper shield termination will result in vibration in the
motor and poor ride quality.
During start-up and then every 30 ms, a position value is read from the
absolute tracks. This initial readout of the absolute position provides the
drive with the commutation angle for permanent magnet motors.
If no absolute and/or zero track is recognized during power-on, these
functions are deactivated. Operation with exclusive utilization of the high-
resolution tracks A and B is possible.
On the rst operation of a permanent magnet motor, it is necessary to
synchronize the encoder position to one of the pole pairs of the motor. See
parameter LE06 for more information and section 5.10.
During normal operation, the difference between the internal absolute
position of the encoder and the measured position value in the drive is
compared. If the two deviate by more than 2.8 degrees, the drive will
trigger the ‘Error Encoder Interface’ fault. Refer to parameter LE12 for more
information.
If there is an excess length of cable (10 feet or less), it is OK to coil it into a
loop in the controller. Maintain a minimum diameter of 1 foot and keep the
cable at least 8 inches away from all high voltage power wires.
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