Why Does the Brushless Drive Receive Modbus Commands Successfully But the Motor Doesn't Rotate?

Among the MODBUS-compatible brushless drives currently sold by STEPPERONLINE, two control modes are provided: Internal Control and External Control. Internal Control refers to using MODBUS RS485 commands to operate the motor, while External Control mode uses the physical input ports on the drive for operation.

When using MODBUS RS485 commands for control, some customers may find that even with all wiring correct, no drive alarm present, and the 485 commands successfully written and acknowledged, the motor still fails to run as expected. The key issue often lies in not switching the drive's control mode.

For example, for the BLD-305S model, the parameter to modify the control mode is shown below:

The specific MODBUS command to switch to Internal Control mode is:

01 06 01 36 00 01 CRC CRC

Similarly, for other brushless drives, please consult the respective drive manual to find the correct register address for modifying the control mode.

However, please note that some drives (e.g., the BLD-510B) automatically switch their control mode to Internal Control after any parameter is modified via RS485 commands. In such cases, the control mode is likely not the cause of the problem. If the issue persists under these circumstances, please contact our technical support for further assistance.

Updated on: 28/11/2025