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B&R DM435
Product Introduction:
The B&R DM435 is a compact, high-performance stepper motor drive from the B&R ACOPOS family. It is designed for precise open-loop and closed-loop position control of 2-phase and 5-phase stepper motors. The DM435 delivers up to 3.5A RMS per phase with advanced microstepping technology, providing smooth motion with minimal vibration and noise. It is ideal for applications requiring precise positioning without the cost and complexity of a servo system with encoder.
Detailed content
Technical Specifications:
| Parameter | Value |
|---|---|
| Mains Supply Voltage | 24V DC to 48V DC (nominal 24V DC) |
| Continuous Output Current per Phase | 3.5 A RMS |
| Peak Output Current per Phase | 5.0 A (for ≤ 2 seconds) |
| Microstepping Resolutions | Full step, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256 |
| Maximum Step Frequency | 500 kHz (with 1/256 microstepping) |
| Control Modes | Step/Direction, Pulse/Direction, CW/CCW, Target Position |
| Communication Interface | POWERLINK, EtherCAT, CANopen, Serial (RS-232/RS-485) |
| Digital Inputs | 4× (Step, Direction, Enable, Home) |
| Digital Outputs | 2× (In-Position, Fault) |
| Operation Temperature | 0°C to +55°C (derating above 40°C) |
| Protection Class | IP20 (with cover: IP54) |
| Dimensions (W×H×D) | 45 mm × 90 mm × 106 mm |
| Weight | Approx. 0.35 kg |
| Conformity | CE, UL, CSA, ATEX Zone 2 |
Functional Features:
- Advanced microstepping up to 1/256 for ultra-smooth motion with minimal resonance
- Closed-loop operation with external encoder feedback (optional) for stall detection
- Integrated POWERLINK and EtherCAT slave for network-based motion control
- Automatic current reduction in standstill to minimize motor heating
- S-curve acceleration/deceleration profiles with configurable jerk limits
- Electronic gear ratio for synchronized multi-axis operation
- Safe Torque Off (STO) per EN 61800-5-2 (SIL2/PLc)
Structural Characteristics:
- DIN rail TS35 or wall mounting
- Screw terminals for power (24-48V DC), motor (A+/A-/B+/B-), encoder, and I/O
- Wire size: 0.5 mm² to 2.5 mm² for motor; 0.14 mm² to 1.5 mm² for signal
- Housing: aluminum die-cast with natural anodized finish
- No external fan — passive cooling via heatsink fins
Working Principle:
The DM435 converts the 24-48V DC supply into a regulated DC bus. A dual H-bridge chopper circuit drives the two motor phases with sinusoidal current waveforms generated by PWM at up to 500 kHz. The microstepping controller divides each full step into up to 256 microsteps, producing near-sinusoidal phase currents that eliminate the jerky motion of full-step operation. The step/direction interface receives pulse trains from the controller, which the drive translates into precise rotor position increments. In closed-loop mode, the encoder feedback is compared to the commanded position to detect and correct missed steps.
Advantages & Highlights:
- Ultra-smooth motion at 1/256 microstepping — ideal for optical alignment, dispensing, and precision positioning
- High step frequency (500 kHz) enables fast traverse speeds even with fine microstepping
- Compact size (45×90×106 mm) — among the smallest stepper drives in its class
- Passive cooling — no fan, zero maintenance, silent operation
- Cost-effective alternative to servo drives for applications where full encoder feedback is not required
Applicable Industries:
- 3D printers and additive manufacturing
- Pick-and-place machines
- Lab automation (pipetting, sample handling)
- Valve positioning (quarter-turn actuators)
- Camera pan/tilt positioning
- Small CNC routers and laser cutters
Installation Requirements:
- Mount on DIN rail TS35 or vertically on a flat surface with heatsink fins unobstructed
- Use shielded twisted-pair cable for step/direction signals (max 10 m)
- Motor cable: shielded, max 5 m (longer cables require output filter)
- Install fuse: 5A fast-blow on the 24V DC supply line
- For EtherCAT/POWERLINK: use shielded CAT5e cable
Usage Precautions:
- Do not exceed 3.5A RMS per phase continuous — derate by 2% per °C above 40°C ambient
- Always use a motor with rated current ≤ 3.5A RMS per phase — oversized motors cause drive overheating
- Enable closed-loop mode only with compatible encoder (incremental, 5V TTL, max 500 kHz)
- Do not disconnect motor while energized — this causes voltage spike and may damage output transistors
- Set microstepping resolution before first operation — changing microstepping mid-operation causes position loss
