It is not necessary to be concerned with cross-wiring the 1
st
and 2
nd
signals. If this wiring
is incorrect, the setup procedure will alert the user (Step D).
Step C.
Specify the Size of the Magnetic Cycle.
Use the command, BM, to specify the size of the brushless motors magnetic cycle in
encoder counts. For example, if you are using a linear motor where the magnetic cycle
length is 62 mm, and the encoder resolution is 1 micron, the cycle equals 62,000 counts.
This can be commanded with the command:
BM 62000 <CR>
On the other hand, if you are using a rotary motor with 4000 counts per revolution and 3
magnetic cycles per revolution (three pole pairs) the command is
BM
1333.333
<CR>
Step D.
Test the Polarity of the DACs and Hall Sensor Configuration.
Use the brushless motor setup command, BS, to test the polarity of the output DACs.
This command applies a certain voltage, V, to each phase for some time T, and checks to
see if the motion is in the correct direction.
The user must specify the value for V and T. For example, the command
BS 2,700 <CR>
will test the brushless 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 occurs 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
24
i
Chapter 2 Getting Started
DMC-14x5/6
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