Possible Causes and Inspection Methods for Abnormal Operation of a Brushless Motor

1. Brushless Motor Fails to Operate

1.1 Wiring Issues

Refer to the brushless motor’s datasheet and the brushless driver’s labeling to verify correct wiring. The corresponding connections are as follows:

1.2 Brushless Driver Not Enabled

Some StepperOnline brushless drivers have different logic for the EN (Enable) port compared to other drivers. Refer to the driver’s manual to determine whether connecting or disconnecting EN and GND enables the motor. Alternatively, try toggling the EN-GND connection to test if the motor starts.

1.3 Incorrect R-SL or R-CS Settings

The R-SL knob on the brushless driver sets the speed limit, while the R-CS knob adjusts the current. If either is set to 0, the motor will not run. Verify that these settings are correct.

1.4 Incorrect Internal/External Control Mode Setting

StepperOnline brushless drivers support two control modes:

• Internal Control: Uses RS485 to control motor operation.

• External Control: Uses the driver’s ports to control motor operation.

If the wrong mode is selected, the driver will not operate the motor. Some drivers automatically switch to Internal Control after modifying parameters via RS485. Check the driver’s manual to confirm the correct control mode setting.

1.5 Driver Triggered an Alarm

If the driver detects a fault, it will illuminate a red LED and stop the motor. If the LED is on:

Use RS485 to read the driver’s alarm registers (refer to the manual).

Some drivers display error codes via LED blinking patterns—check the manual for decoding.

1.6 Incorrect Driver Parameter Settings

If parameters are misconfigured, the motor may not run. Verify all driver settings.

Note:
Except for BLD-510S and BLD-510B, other StepperOnline brushless drivers are not fully compatible with stepperonline_bldc_software_V2.7. Using this software may write parameters to incorrect registers. For these drivers, we currently recommend using alternative RS485 serial software to modify motor parameters.

1.7 Brushless Motor or Driver Damaged

If the brushless motor still fails to operate after all the above checks and tests, the motor or driver may be damaged. If you have spare brushless motors or drivers, try swapping them to isolate the faulty component.

2. Brushless Motor Speed Does Not Match Expectations

2.1 Incorrect R-SL Setting on the Brushless Driver

The R-SL knob on the brushless driver limits the motor’s maximum speed. If set too low, the motor may not reach higher RPM. Verify that the R-SL knob is adjusted correctly.

2.2 Incorrect "Pairs of Poles" Parameter Setting

The brushless driver’s "pairs of poles" parameter is critical for speed control. Refer to the motor’s datasheet to confirm this setting.
Note: The driver requires pairs of poles (not total poles). Typically, pairs of poles = total poles / 2.

2.3 Calculation Error When Converting Register Parameters to Actual Speed

If reading motor speed from register parameters, ensure correct calculation:

a. Register values are in hexadecimal and must be converted to decimal.
Note: Data format is little-endian (LSB first). For example, a register value of C8 00 should be interpreted as 00 C8 (hex) = 200 (decimal).

b. Multiply the decimal value by 20, then divide by the motor’s total poles to obtain RPM.
Example:

• Motor poles = 4 (pairs of poles = 2)

• Register speed value = C8 00 → 200 (decimal)

• Actual speed = (200 × 20) / 4 = 1000 RPM

Note: Due to Hall sensor precision limitations, the actual speed may have a ±5% error.

If the brushless motor still fails to operate normally after the above inspections and tests, please contact StepperOnline's technical support and provide the test results or videos. We will assist you in resolving the issue as soon as possible.

Updated on: 25/06/2025