MMP SA-2550A
Page 20 of
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Midwest Motion Products
DESIGN, MANUFACTURING & DISTRIBUTION - MOTION CONTROL EQUIPMENT
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A shunt regulator may be necessary to dissipate the energy regenerated by the system. See the section on regenerative braking,
pages 13-15 for more details.
Invalid Hall State
Brushless drives have 3 Hall sensor inputs that determine a Hall state. The drive will fault if an invalid Hall state is detected.
If the LED is red or changing between red and green as the motor rotates, it could be an indication of an invalid Hall state.
Connect only the Hall sensors to the drive and apply power.
Make sure the 60 or 120 phasing switch is in the correct position according to motor.
Verify that all Hall sensor inputs are wired correctly to the drive.
Measure the voltage levels for all Hall sensor inputs. The voltage levels should change between 0 and 5V as the motor rotates.
If using a motor with both Hall sensors and an encoder, make sure the supply for the feedback has enough power. Drives with
onboard Hall sensor power rated at 30mA won’t have enough current and a separate supply will be required.
If using a separate supply for the Hall sensors, make sure the ground reference for the supply is tied to the signal ground of
the drive.
Rotate the motor and verify that ALL Hall sensor inputs are changing and follow the Hall sequence in the table below.
60 Degree 120 Degree
60 Degree
120 Degree
Hall A
Hall B
Hall C
Hall A
Hall B
Hall C
1
0
0
1
0
0
1
1
0
1
1
0
1
1
1
0
1
0
Valid
0
1
1
0
1
1
Green
0
0
1
0
0
1
LED
0
0
0
1
0
1
1
0
1
1
1
1
Invalid Red
0
1
0
0
0
0
LED
Table 1. Valid and invalid hall sensor states per brushless motor phase.
1 – Indicates high level hall sensor input (5V)
0 – Indicates low level hall sensor input (0V)
Drive Inhibited
For standard inhibits, the drive disables when the inhibit pin is grounded. For inverted inhibits, the drive enables when the inhibit
pin grounded.
A drive with standard inhibits has a 0 ohm SMT resistor labeled “J1” installed on the PCB. Removing this jumper will invert the
inhibits. Amplifiers can be ordered with the J1 jumper removed and have a “-INV” on the end of the part number, e.g., 12A8-INV.
Some drives have a DIP switch to invert the inhibits. This option will be listed on the drive datasheet if available.
Note: Some drives have directional inhibits (+INHIBIT / -INHIBIT) which inhibit motion in their respective directions but do NOT
cause a red LED.
Measure the voltage of the inhibit pin. It should read 5V if left open and 0 if grounded.
Verify if the drive is configured for standard or inverted inhibits.
If your controller is disabling the drive, verify under what conditions this will occur, e.g., position following error, position limit
reached, etc.
Over-temperature
The drive will fault if the heat sink base plate temperature exceeds 65C.
Safely measure the heat sink base plate temperature.
If the temperature exceeds 65C, additional cooling may be necessary.
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