1. Introduction
The Makerbase MKS SERVO28D and MKS SERVO35D are advanced closed-loop stepper motor drivers designed to meet the demands of various applications, including small robotic arms, 3D printers, engraving machines, writers, automation products, and e-sports equipment. These drivers feature pulse interfaces and optional RS485/CAN interfaces, integrating efficient FOC (Field-Oriented Control) vector algorithms. By utilizing high-precision encoders, they provide position feedback to effectively prevent motor step loss, ensuring precise and reliable operation.
2. Key Features
- Supports 6 working modes: Pulse interface (open loop, closed loop, FOC mode), Serial interface (open loop, closed loop, FOC mode).
- Supports MODBUS-RTU communication protocol (RS485 version).
- High-performance FOC vector control algorithm with torque, speed, and position three-loop control.
- Supports curve acceleration and deceleration for smoother motor start and stop.
- Supports single-turn unlimited zeroing function.
- Supports multi-turn limit zeroing and left/right limit functions.
- Supports direct setting of zero point function.
- Supports relative position and absolute position control modes.
- Supports 1 to 256 arbitrary subdivision steps.
- Built-in 256-step subdivision interpolation algorithm for super quiet and ultra-low vibration motor operation.
- Maximum input pulse frequency of 160KHz, maximum speed 3000RPM+.
- Real-time update of motor angle information (motor enabled or disabled).
- Onboard industrial-grade high-precision 16384-line magnetic encoder.
- Onboard 4 high-power MOSFETs, 40V/20A.
- Built-in RS-485 interface with 256 slave addresses, supporting group address (RS485 version).
- Built-in CAN interface with 2048 slave addresses, supporting group address (CAN version).
- Maximum operating current 3.0A, MOSFET continuous operating current 20A (at 25 °C).
- Can be connected to an external OLED display screen and buttons for parameter modification, automatic saving, and immediate effect.
- Includes built-in stall protection function.
- Features encoder self-calibration function.
- One-click quick restore to factory settings.
- Stable high-speed performance, smooth running, no shaking, and emergency stop capability.
- Provides host computer (open source), STM32/Arduino usage routines.
3. Technical Specifications
| Feature | Specification |
|---|---|
| Type | Voltage Regulator (Closed Loop Stepper Motor Driver) |
| Origin | Mainland China |
| Condition | New |
| Max Input Pulse Frequency | 160 KHz |
| Max Speed | 3000 RPM+ |
| Encoder Resolution | 16384 lines (industrial-grade high-precision magnetic encoder) |
| MOSFETs | 4 high-power, 40V/20A |
| Max Operating Current | 3.0A |
| MOSFET Continuous Operating Current | 20A (at 25 °C) |
| RS-485 Interface (RS485 version) | Built-in, 256 slave addresses, supports group address (MODBUS-RTU protocol) |
| CAN Interface (CAN version) | Built-in, 2048 slave addresses, supports group address |
| Subdivision Steps | 1 to 256 (arbitrary) |
4. Included Components
The MKS SERVO28D/35D driver package typically includes:
- MKS SERVO28D or MKS SERVO35D Closed Loop Stepper Motor Driver board.
- Connecting cables (for motor and power).
- Mounting hardware (screws, washers).
- Optional: External OLED display and buttons (if purchased separately or as part of a specific kit).
5. Setup and Wiring
Before connecting the MKS SERVO driver, ensure all power is disconnected. Refer to the specific wiring diagrams for your version (RS485 or CAN) to ensure correct connections.
5.1 MKS SERVO28D/35D RS485 Version Wiring
5.2 MKS SERVO28D/35D CAN Version Wiring
5.3 Driver Board Layouts
Familiarize yourself with the pinouts and component placement on the driver boards:
6. Operating Modes
The MKS SERVO drivers support six distinct operating modes:
- Pulse Interface - Open Loop Mode: Standard stepper motor control using pulse signals without encoder feedback for position correction.
- Pulse Interface - Closed Loop Mode: Utilizes pulse signals for control and encoder feedback for real-time position correction, preventing step loss.
- Pulse Interface - FOC Mode: Advanced Field-Oriented Control using pulse signals, offering high efficiency and smooth operation with encoder feedback.
- Serial Interface (RS485/CAN) - Open Loop Mode: Control via serial communication (RS485 or CAN) without encoder feedback for position correction.
- Serial Interface (RS485/CAN) - Closed Loop Mode: Control via serial communication with encoder feedback for precise position control and step loss prevention.
- Serial Interface (RS485/CAN) - FOC Mode: Advanced Field-Oriented Control via serial communication, providing high efficiency and smooth operation with encoder feedback.
The specific mode can be configured via the host computer software or an external OLED display (if connected).
7. Configuration and Parameter Settings
The MKS SERVO drivers offer extensive configuration options to tailor performance to your application. Parameters can be adjusted using the provided host computer software or an optional external OLED display with buttons.
- Subdivision Steps: Configure micro-stepping from 1 to 256 for smoother motion.
- Zeroing Functions:
- Single-turn unlimited zeroing.
- Multi-turn limit zeroing.
- Left and right limit functions.
- Direct setting of zero point.
- Position Control Modes: Switch between relative and absolute position control.
- Encoder Self-Calibration: Perform encoder self-calibration for optimal accuracy.
- Factory Reset: A one-click function is available to restore all settings to factory defaults.
Refer to the host computer software documentation or the OLED display interface for detailed instructions on parameter adjustment.
8. User Tips
- Always ensure proper grounding and power supply voltage to prevent damage to the driver and motor.
- When using serial communication (RS485/CAN), ensure the correct protocol (MODBUS-RTU for RS485) and slave addresses are configured.
- For optimal performance and quiet operation, utilize the built-in 256-step subdivision interpolation algorithm.
- If experiencing unexpected behavior, try performing an encoder self-calibration or a factory reset as a first troubleshooting step.
- Leverage the provided host computer software and STM32/Arduino routines for easier integration and advanced control.
9. Troubleshooting
- Motor not moving or losing steps:
- Check all wiring connections, especially motor coils and power supply, against the diagrams in Section 5.
- Verify the power supply voltage is within the 12V-24V range.
- Ensure the correct operating mode (open loop, closed loop, FOC) is selected and configured.
- If in closed-loop or FOC mode, check the encoder connection and perform an encoder self-calibration.
- Reduce the maximum operating current or acceleration/deceleration settings if the motor is stalling.
- Check for any mechanical obstructions preventing motor movement.
- Communication issues (RS485/CAN):
- Verify the RS485 A/B or CAN H/L connections are correct and not reversed.
- Ensure the correct communication protocol (MODBUS-RTU for RS485) and baud rates are matched between the driver and the host controller.
- Check the slave address configuration to ensure it is unique and correctly set.
- Ensure no short-circuit cap is connected for stand-alone serial communication.
- OLED display not working:
- Ensure the OLED display is correctly connected to the dedicated port on the driver board.
- Check for any loose connections or damage to the display cable.
10. Maintenance
The MKS SERVO drivers are designed for reliable operation with minimal maintenance. However, following these guidelines can help ensure longevity:
- Keep Clean: Regularly clean the driver board to prevent dust and debris accumulation, which can affect heat dissipation and component performance. Use a soft, dry brush or compressed air.
- Environmental Conditions: Operate the driver within its specified environmental conditions (temperature, humidity) to avoid damage.
- Connection Integrity: Periodically check all wiring connections for tightness and signs of wear or corrosion. Loose connections can lead to intermittent operation or damage.
- Heat Management: Ensure adequate airflow around the driver, especially during continuous high-current operation, to prevent overheating.
11. Warranty and Support
For warranty information, technical support, and access to the latest documentation, host computer software, and usage routines (STM32/Arduino), please refer to the official Makerbase website or contact your vendor. Ensure you have your product model (MKS SERVO28D or MKS SERVO35D) and any relevant purchase details available when seeking support.
12. Frequently Asked Questions
No specific FAQs are available at this time. Please refer to the troubleshooting section or contact support for assistance.
