SMD-M860 Bipolar Microstep Stepper Motor Driver – 24–80VDC
SMD-M860 Bipolar Microstep Stepper Motor Driver
Restore smooth, controlled movement in a compatible laser engraving or cutting machine with the M860 stepper motor driver.
The M860 receives pulse and direction commands from the machine controller and converts them into controlled electrical current for a connected stepper motor. It is commonly used to operate larger motors and machine axes that require more current than lower-capacity stepper drivers can provide.
The driver offers eight selectable current settings and sixteen selectable pulse-per-revolution settings. Properly matching these settings to the original driver, motor, and machine controller helps maintain accurate travel, dependable torque, smooth motion, and controlled operating temperatures.
Key Features
- Bipolar digital microstep motor driver
- 24–80VDC input range
- Eight selectable motor-current settings
- Reference-current settings from 2.00A to 6.00A
- Corresponding peak-current settings from 2.40A to 7.20A
- Sixteen selectable microstep resolutions
- Settings from 400 to 51,200 pulses per revolution
- Pulse, direction, and enable inputs
- Optically isolated, TTL-compatible control signals
- Pulse input frequency up to 200kHz
- Pulse/direction and CW/CCW control support
- Selectable half or full standstill current
- Automatic idle-current reduction
- Anti-resonance control for smoother movement
- Motor identification and automatic parameter adjustment
- Soft startup to reduce sudden movement when powered on
- Built-in overcurrent and overvoltage protection
- Power and alarm status indicator
- Integrated aluminum heat sink
- Removable terminal connectors included
Motor-Current Settings
DIP switches SW1 through SW3 select the motor operating current.
The diagram printed on the M860 lists both reference current and peak current. These values should not be treated as interchangeable when comparing the driver with a motor specification or another driver model.
| Reference Current | Peak Current | SW1 | SW2 | SW3 |
|---|---|---|---|---|
| 2.00A | 2.40A | ON | ON | ON |
| 2.57A | 3.08A | OFF | ON | ON |
| 3.14A | 3.77A | ON | OFF | ON |
| 3.71A | 4.45A | OFF | OFF | ON |
| 4.28A | 5.14A | ON | ON | OFF |
| 4.86A | 5.83A | OFF | ON | OFF |
| 5.43A | 6.52A | ON | OFF | OFF |
| 6.00A | 7.20A | OFF | OFF | OFF |
The selected current must be appropriate for the connected motor and its wiring configuration.
A setting that is too low may result in weak movement, stalling, or missed steps. A setting that is too high may cause excessive motor and driver temperatures.
SW4 Standstill-Current Setting
SW4 controls the current supplied to the motor while the axis is stopped.
- SW4 OFF: Half standstill current
- SW4 ON: Full standstill current
With the half-current setting selected, the driver reduces the current after the motor stops receiving movement pulses. This helps reduce motor and driver heat while the axis is idle.
A replacement driver should normally use the same SW4 position as the original driver unless the motor and machine requirements have been properly verified.
Pulse-Per-Revolution Settings
DIP switches SW5 through SW8 select the number of controller pulses required for one complete motor revolution.
| Pulses per Revolution | Microstep Division | SW5 | SW6 | SW7 | SW8 |
|---|---|---|---|---|---|
| 400 | 1/2 | ON | ON | ON | ON |
| 800 | 1/4 | OFF | ON | ON | ON |
| 1,600 | 1/8 | ON | OFF | ON | ON |
| 3,200 | 1/16 | OFF | OFF | ON | ON |
| 6,400 | 1/32 | ON | ON | OFF | ON |
| 12,800 | 1/64 | OFF | ON | OFF | ON |
| 25,600 | 1/128 | ON | OFF | OFF | ON |
| 51,200 | 1/256 | OFF | OFF | OFF | ON |
| 1,000 | 1/5 | ON | ON | ON | OFF |
| 2,000 | 1/10 | OFF | ON | ON | OFF |
| 4,000 | 1/20 | ON | OFF | ON | OFF |
| 5,000 | 1/25 | OFF | OFF | ON | OFF |
| 8,000 | 1/40 | ON | ON | OFF | OFF |
| 10,000 | 1/50 | OFF | ON | OFF | OFF |
| 20,000 | 1/100 | ON | OFF | OFF | OFF |
| 40,000 | 1/200 | OFF | OFF | OFF | OFF |
These microstep divisions assume a standard 1.8-degree, 200-step motor.
The replacement driver should normally use the same SW5 through SW8 positions as the original driver. Changing these settings without updating the machine controller can cause incorrect travel distances, inaccurate positioning, or unexpected changes in axis speed.
Control-Signal Terminals
The control terminals printed on the M860 are arranged as follows:
- DIR−: Negative direction-signal connection
- DIR+: Positive direction-signal connection
- PUL−: Negative pulse-signal connection
- PUL+: Positive pulse-signal connection
- ENA−: Negative enable-signal connection
- ENA+: Positive enable-signal connection
The enable terminals may be left unused in some machine configurations. Always match the replacement wiring to the original driver and machine controller.
The M860 supports standard pulse-and-direction control. It can also support clockwise and counterclockwise pulse control through its internal configuration.
Power and Motor Terminals
The high-voltage power and motor terminals printed on the driver are:
- A+: Motor phase A positive
- A−: Motor phase A negative
- B+: Motor phase B positive
- B−: Motor phase B negative
- VDC: Positive DC power input
- GND: DC power-supply ground
The power supply must remain within the driver’s 24–80VDC input range, including voltage changes and back voltage created as the motor slows down.
The motor wires must be connected as the correct A and B phase pairs. Incorrect phase wiring may cause vibration, rough movement, excessive noise, movement in the wrong direction, or failure to rotate.
Product Specifications
- Rabbit Laser USA part number: SMD-M860
- Driver model: M860
- Product type: Bipolar digital microstep motor driver
- Input voltage: 24–80VDC
- Recommended nominal supply range: Up to approximately 68VDC to allow room for voltage fluctuation and motor back voltage
- Current settings: Eight
- Reference-current range: 2.00–6.00A
- Peak-current range: 2.40–7.20A
- Microstep settings: Sixteen
- Pulse range: 400–51,200 pulses per revolution
- Microstep range: 1/2 through 1/256 and 1/5 through 1/200
- Maximum pulse-input frequency: 200kHz
- Minimum recommended pulse width: 2.5 microseconds
- Control inputs: Pulse, direction, and enable
- Control modes: Pulse/direction and CW/CCW
- Signal compatibility: 5V TTL compatible
- Signal isolation: Optical isolation
- Motor outputs: A+, A−, B+, and B−
- Power inputs: VDC and GND
- Standstill-current selection: Half or full current
- Status indicator: Alarm and power
- Body dimensions: Approximately 5.63 × 3.82 × 1.89 inches
- Body dimensions: Approximately 143 × 97 × 48mm
- Overall mounting length: Approximately 5.94 inches or 151mm
- Heat sink and terminal connectors: Included
Compatibility Notice
Stepper motor drivers that look similar may have different voltage ranges, current tables, microstep settings, signal requirements, terminal orders, or internal control methods.
Before ordering, compare the following with the original driver:
- M860 model number
- 24–80VDC input requirement
- Reference and peak current values
- SW1 through SW4 positions
- Pulse-per-revolution setting
- SW5 through SW8 positions
- DIR, PUL, and ENA terminal arrangement
- VDC and GND power connections
- Motor phase connections
- Physical size
- Mounting-hole locations
Do not select a replacement based only on the general M860 name or the appearance of the enclosure.
Important Installation Information
Disconnect the laser machine from electrical power before inspecting or replacing the stepper motor driver.
Photograph and label every wire and DIP-switch position before removing the original driver. Copying the original switch positions is normally the safest starting point when installing a direct replacement.
Confirm the VDC and GND connections before applying power. Reversing the DC power polarity may immediately damage the driver.
Never connect or disconnect the motor while the driver is powered. The voltage created by disconnecting an energized motor can damage the driver’s output circuitry.
Mount the driver vertically when possible and leave enough open space around the heat sink for heat to escape. Forced airflow may be needed when the driver is installed in a warm or crowded electrical cabinet.
After installation, test the axis at a low speed before returning the machine to normal operation.
Troubleshooting a Motion Problem
Stepper-driver problems may cause symptoms such as:
- An axis that does not move
- A motor that vibrates without rotating
- Jerky or uneven movement
- Missed steps
- Incorrect travel distance
- Inaccurate positioning
- Movement in only one direction
- Excessive motor or driver heat
- A flashing alarm indicator
- Intermittent axis operation
These symptoms do not always mean the driver has failed. Similar problems may be caused by incorrect DIP-switch settings, loose wiring, electrical interference, damaged motor cables, incorrect phase pairing, low power-supply voltage, mechanical binding, controller settings, or a damaged stepper motor.
Confirm Compatibility Before Ordering
Not sure whether the SMD-M860 is correct for your laser machine? Contact Rabbit Laser USA with your machine model and clear photos of the original driver, wiring terminals, and DIP-switch positions. Our technical support team can help confirm compatibility before you order.