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32 • Chapter 2 Getting Started DMC-1700/1800
will test the X axis with a voltage of 2 volts, applying it for 700 millisecond for each phase.
In response, this test indicates whether the DAC wiring is correct and will indicate an
approximate value of BM. If the wiring is correct, the approximate value for BM will
agree with the value used in the previous step.
Note: In order to properly conduct the brushless setup, the motor must be allowed to move a
minimum of one magnetic cycle in both directions.
Note: When using Galil Windows software, the timeout must be set to a minimum of 10
seconds (time-out = 10000) when executing the BS command. This allows the software
to retrieve all messages returned from the controller.
If Hall Sensors are Available:
Since the Hall sensors are connected randomly, it is very likely that they are wired in the
incorrect order. The brushless setup command indicates the correct wiring of the Hall
sensors. The hall sensor wires should be re-configured to reflect the results of this test.
The setup command also reports the position offset of the hall transition point and the zero
phase of the motor commutation. The zero transition of the Hall sensors typically occur
at 0°, 30° or 90° of the phase commutation. It is necessary to inform the controller
about the offset of the Hall sensor and this is done with the instruction, BB.
Step E. Save Brushless Motor Configuration
It is very important to save the brushless motor configuration in non-volatile memory. After
the motor wiring and setup parameters have been properly configured, the burn
command, BN, should be given.
If Hall Sensors are Not Available:
Without hall sensors, the controller will not be able to estimate the commutation phase of
the brushless motor. In this case, the controller could become unstable until the
commutation phase has been set using the BZ command (see next step). It is highly
recommended that the motor off command be given before executing the BN command.
In this case, the motor will be disabled upon power up or reset and the commutation
phase can be set before enabling the motor.
Step F. Set Zero Commutation Phase
When an axis has been defined as sinusoidally commutated, the controller must have an
estimate for commutation phase. When hall sensors are used, the controller automatically
estimates this value upon reset of the controller. If no hall sensors are used, the controller
will not be able to make this estimate and the commutation phase must be set before
enabling the motor.
If Hall Sensors are Not Available:
To initialize the commutation without Hall effect sensor use the command, BZ. This
function drives the motor to a position where the commutation phase is zero, and sets the
phase to zero.
The BZ command argument is a real number which represents the voltage to be applied
to the amplifier during the initialization. When the voltage is specified by a positive
number, the initialization process ends up in the motor off (MO) state. A negative
number causes the process to end in the Servo Here (SH) state.
Warning: This command must move the motor to find the zero commutation phase.
This movement is instantaneous and will cause the system to jerk. Larger applied
voltages will cause more severe motor jerk. The applied voltage will typically be
sufficient for proper operation of the BZ command. For systems with significant friction,