1. Introduction
The Makerbase MKS SERVO42D is a high-performance closed-loop stepper motor driver designed to meet the demands of various applications including small robotic arms, 3D printers, engraving machines, and automation products. This driver integrates a pulse interface and offers communication options via RS485 or CAN interfaces. Featuring an efficient FOC vector algorithm and a high-precision encoder, it effectively prevents motor step loss through precise position feedback, ensuring smooth and reliable operation.
Figure 1: MKS SERVO42D Closed Loop Stepper Motor Driver
2. Key Features
- Support 6 working modes: pulse interface (open loop, closed loop, FOC mode), serial interface (open loop, closed loop, FOC mode).
- Support MODBUS-RTU communication protocol (RS485 version).
- High-performance FOC vector control algorithm, torque, speed, and position three-loop control.
- Support curve acceleration and deceleration, motor start and stop are smoother.
- Support single-turn unlimited zeroing function.
- Support multi-turn limit zeroing and left and right limit functions.
- Support direct setting of zero point function.
- Support relative position and absolute position control modes.
- Support 1~256 arbitrary subdivision steps.
- Built-in 256-step subdivision interpolation algorithm, the motor runs super quiet and ultra-low vibration.
- Maximum input pulse frequency 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 8 high-power MOSFETs, 40V/20A.
- Built-in RS-485 interface, 256 slave addresses, support group address (RS485 version).
- Built-in CAN interface, 2048 slave addresses, support group address (CAN version).
- Maximum operating current 3.0A, MOSFET continuous operating current 20A (25 °C).
- Onboard OLED display screen and buttons make it easy to modify parameters, automatically save and take effect immediately.
- With built-in stall protection function.
- With encoder self-calibration function.
- One-click quick restore to factory settings.
- Stable high-speed performance, smooth operation, no shaking, and emergency stop.
- Integrated aluminum alloy shell, effective heat dissipation, the motor works more stably with continuous high current.
- Provide host computer (open source), STM32/Arduion usage routines.
- Support unlimited switch return to zero function.
3. Technical Specifications
| Feature | Specification |
|---|---|
| Type | Voltage Regulator (Stepper Motor Driver) |
| Origin | Mainland China |
| Condition | New |
| Max Operating Current | 3.0A |
| MOSFET Continuous Operating Current | 20A (at 25 °C) |
| Max Input Pulse Frequency | 160KHz |
| Max Speed | 3000 RPM+ |
| Encoder | Industrial-grade high-precision 16384-line magnetic encoder |
| MOSFETs | 8 high-power MOSFETs, 40V/20A |
| Communication Interfaces | RS485 (MODBUS-RTU) or CAN |
| Subdivision Steps | 1~256 arbitrary subdivision steps |
| Control Algorithm | FOC vector control algorithm |
4. Package Contents
The MKS SERVO42D package typically includes the following components:
- MKS SERVO42D Closed Loop Stepper Motor Driver board (RS485 or CAN version)
- Wiring harness for motor connection (4-pin, colored wires)
- Mounting screws
- Washers
- Small button/cap (possibly for reset or configuration)
Figure 2: Typical contents of the MKS SERVO42D (RS485 version) package.
5. Installation and Wiring
Careful wiring is essential for the correct and safe operation of the MKS SERVO42D driver. Ensure all power is disconnected before making any connections.
5.1. RS485 Version Wiring
Figure 3: MKS SERVO42D RS485 V1.0 PCB Layout (Front and Back) showing pin assignments.
| Pin Label | Description |
|---|---|
| V+ | Motor Power Supply Input (e.g., 12-24V DC) |
| GND | Ground for Power Supply |
| A+, A-, B+, B- | Motor Phase Windings (connect to stepper motor coils) |
| EN | Enable Signal Input (active low, typically) |
| STP | Step Pulse Input |
| DIR | Direction Signal Input |
| 5V | 5V Output (for external logic, limited current) |
| COM | Common Ground for Control Signals |
| 485R, 485S | RS485 Communication Lines (connect to RS485 master device) |
5.2. CAN Version Wiring
Figure 4: MKS SERVO42D CAN V1.0 PCB Layout (Front and Back) showing pin assignments.
| Pin Label | Description |
|---|---|
| V+ | Motor Power Supply Input (e.g., 12-24V DC) |
| GND | Ground for Power Supply |
| A+, A-, B+, B- | Motor Phase Windings (connect to stepper motor coils) |
| EN | Enable Signal Input (active low, typically) |
| STP | Step Pulse Input |
| DIR | Direction Signal Input |
| 5V | 5V Output (for external logic, limited current) |
| COM | Common Ground for Control Signals |
| CAN L, CAN H | CAN Bus Communication Lines (connect to CAN bus network) |
General Wiring Notes:
- Ensure correct polarity for power connections (V+ and GND).
- Connect motor phase windings (A+, A-, B+, B-) to the corresponding terminals on the driver. Refer to your stepper motor's datasheet for correct winding identification.
- Control signals (EN, STP, DIR) should be connected to your microcontroller or control board.
- For serial communication (RS485 or CAN), connect the respective lines to your master device or network.
6. Operation
The MKS SERVO42D supports various operating modes and control methods to suit different application requirements.
6.1. Working Modes
The driver supports 6 distinct working modes:
- Pulse Interface Modes:
- Open Loop Mode
- Closed Loop Mode
- FOC (Field-Oriented Control) Mode
- Serial Interface Modes (RS485/CAN):
- Open Loop Mode
- Closed Loop Mode
- FOC (Field-Oriented Control) Mode
The FOC vector control algorithm provides precise torque, speed, and position control, enhancing motor performance and efficiency.
6.2. Control Functions
- Acceleration/Deceleration: Supports curve acceleration and deceleration for smoother motor starts and stops.
- Zeroing Functions:
- Single-turn unlimited zeroing.
- Multi-turn limit zeroing.
- Left and right limit functions.
- Direct setting of zero point.
- Unlimited switch return to zero.
- Position Control: Supports both relative and absolute position control modes.
- Subdivision: Configurable 1 to 256 arbitrary subdivision steps, with a built-in 256-step interpolation algorithm for quiet and low-vibration operation.
- Real-time Angle Information: Motor angle information is updated in real-time, regardless of whether the motor is enabled or disabled.
7. Configuration and Parameter Adjustment
The MKS SERVO42D features an onboard OLED display and buttons for easy parameter modification. Changes are automatically saved and take effect immediately.
- OLED Display: Provides visual feedback on current settings and motor status.
- Buttons (Menu, Enter, Next): Navigate through menus and adjust parameters directly on the device.
- Factory Reset: A one-click function is available to quickly restore the device to its default factory settings.
For advanced configuration and monitoring, a host computer application (open source) is provided, along with usage routines for STM32 and Arduino platforms.
8. Troubleshooting
This section provides guidance on common issues you might encounter with the MKS SERVO42D driver.
- Motor Not Moving/Stalling:
- Check power supply voltage and current capacity.
- Verify motor wiring (A+, A-, B+, B-) is correct and secure.
- Ensure the EN (Enable) signal is active (typically low).
- Check step (STP) and direction (DIR) signals from your controller.
- The driver has built-in stall protection; check if it's being triggered due to excessive load or incorrect current settings.
- Inaccurate Positioning:
- Perform encoder self-calibration.
- Verify the encoder connection is secure.
- Check for mechanical issues in the system (e.g., binding, loose couplings).
- Ensure the correct subdivision steps are configured.
- Communication Issues (RS485/CAN):
- Verify communication wiring (485R/485S or CAN L/CAN H) and termination resistors if applicable.
- Check baud rates and slave addresses for consistency between the driver and master device.
- Ensure the correct communication protocol (MODBUS-RTU for RS485) is being used.
- Overheating:
- Ensure adequate ventilation around the driver. The integrated aluminum alloy shell aids in heat dissipation, but extreme ambient temperatures or continuous high current operation may require additional cooling.
- Reduce motor current if possible without affecting performance.
- Unexpected Behavior:
- Try restoring to factory settings using the onboard buttons.
- Consult the provided host computer software or STM32/Arduino routines for diagnostic tools.
9. Maintenance
The MKS SERVO42D is designed for robust operation with minimal maintenance. Follow these guidelines to ensure longevity:
- Cleaning: Keep the driver free from dust and debris. Use a soft, dry brush or compressed air to clean the heatsink fins periodically.
- Environmental Conditions: Operate the driver within its specified temperature and humidity ranges. Avoid exposure to moisture, corrosive gases, or excessive vibrations.
- Connections: Periodically check all wiring connections to ensure they are secure and free from corrosion. Loose connections can lead to intermittent operation or damage.
- Firmware Updates: Check the manufacturer's website for any available firmware updates that may improve performance or add new features. Follow the provided instructions carefully for any update procedures.
10. Support and Resources
For further assistance and detailed technical information, please refer to the following resources:
- Host Computer Software: Open-source host computer software is available for advanced configuration, monitoring, and diagnostics.
- Programming Routines: Example usage routines for STM32 and Arduino platforms are provided to help with integration into your projects.
- Manufacturer Website: Visit the Makerbase official website for the latest documentation, downloads, and community support.
