Logosol Absolute Positioning Servo Drive LS-173AP
Doc # 712173008 / Rev. 1.06, 05/09/2002
Logosol, Inc.
••
1155 Tasman Drive
••
Sunnyvale, CA 94089 Tel: (408) 744-0974
••
www.logosolinc.com 18
would be programmed as 0.0021 x 2
16
or 137. Position is programmed as a straight 32-bit
quantity with no fractional component. Note that if the servo rate divisor is modified, the time
dependent velocity and acceleration parameters will also have to be modified.
PWM Mode Operation
If the position servo is disabled, the motor is operated in a raw PWM output mode and no
trapezoidal or velocity profiling is performed. In this mode, a user specified PWM value is
outputted directly to the amplifier. The maximum PWM value is 255 and corresponding to
100% duty cycle. Command position is continually updated to match the actual position of the
motor and there will be no abrupt jump in the motor’s position when position or velocity modes
are entered. Also while the position servo is disabled, the command velocity is continually
updated to match the actual velocity of motor. Thus, when velocity mode is entered, there will
be no discontinuity in the motor’s velocity. (Trapezoidal profile motions, however, will still force
the motor to begin at zero velocity.).
Absolute positioning mode
External voltage source or potentiometer connected to ADC input is used for absolute
positioning. In this mode
Analog Target Value
(ATV) is loaded using
Load Trajectory
command. To move to an absolute position, load a velocity and acceleration (if not already
loaded), and ATV (
Analog Target Value
). The ATV will be used as an 8-bit target position and
the controller will start a smooth stop when the A/D value is equal to the loaded ATV. The
direction bit is calculated internally to move in the direction of the command position (ATV).
The
Position Servo
bit should be set and
Velocity Mode
bit should be set. The
Start Now
bit
can be set, or a
Start Motion
command can be used later. After the motion is started, the
Move
Done
bit in the
Status Byte
will remain zero until the actuator has reached the goal position
(A/D = ATV) and the motor has finished decelerating. Issuing a
Stop Motor
command (with
Motor Off
,
Stop Smoothly
, or
Stop Abruptly
), or a servo positioning error will terminate the
Absolute Positioning
mode until a new command is issued.
Connecting Brushless or Brush Type Motor
LS-173AP is capable of driving brushless commutated (AC) and brush (DC) type motors. No
jumpers or other setting are required. If there are no Hall sensors connected to “ENCODER
AND COMMUTATOR”, LS-173AP drives the motor as brush (DC) type. The positive motor
lead should be connected to “AC1 or DC+” terminal and negative to “AC2 or DC-“ terminal of
“MOTOR AND POWER” connector. If Hall sensors are detected, LS-173AP performs
commutation according to their state.
Often, connecting the brushless motor phases is difficult because of the different terms and
signal names, which different manufactures are using. Here is a simple procedure that may be
used.
Connect the motor commutation sensors to LS-173AP “ENCODER AND COMMUTATOR”
connector according to the next table with most common manufacture signal names.
LS-173AP Encoder & Sensor Connector signal
Motor manufacture signal name
S1
R
U
A
S1
S2
S
V
B
S2
S3
T
W
C
S3
Connect the commutator power leads to GND and +5V. Connect the encoder and its power
lines to the same connector. Connect the three motor leads to “AC1 or DC+”, “AC2 or DC-“,
“AC3 or NC” of LS-173AP “MOTOR AND POWER” connector using the same order as for the
commutation sensors. Power on LS-173AP. Initialize the controller. Rotate motor shaft CW
