Wiring Guide for Stepper Driver

A stepper motor driver is the core interface unit connecting a controller (PLC, microcontroller/MCU, or motion control board) to a stepper motor. Standard stepper driver wiring is organized into three main functional blocks: Control Signal Terminals, Motor Power Terminals, and DC Power Supply Terminals.

The control input circuit uses optocoupler isolation. Depending on the controller's output stage (NPN, PNP, or Differential), three wiring topologies are available:

• Concept: Connect all positive terminals (PUL+, DIR+, ENA+) together to the positive supply (+5V or +24V).
• Trigger: Activated when the controller switches the corresponding negative pin (PUL-, DIR-, ENA-) to GND (0V / Low level).

• Concept: Connect all negative terminals (PUL-, DIR-, ENA-) together to the controller's GND (0V).
• Trigger: Activated when the controller outputs a High level (+5V or +24V) to the positive pin (PUL+, DIR+, ENA+).

• Concept: Connect each signal via a dedicated twisted pair (PUL+/PUL-, DIR+/DIR-, ENA+/ENA-) driven by line-driver ICs (e.g., AM26LS31/RS-422 standard).

⚠️ Signal Voltage & Current-Limiting Resistors:

• The internal optocouplers are typically rated for 5V logic.
• If the controller uses a 24V signal voltage:
  • Drivers with built-in wide-range input (5V–24V auto-sensing) can be connected directly.
  • If the driver specifies 5V-only inputs, a 1.5 kΩ~2.2 kΩ (1/4W) resistor MUST be wired in series with each signal line to prevent burning out the optocouplers.

For standard 2-phase 4-wire hybrid stepper motors:

The two wires of Phase A form a continuous closed coil inside the motor, as do the two wires of Phase B. Phase A and Phase B are electrically isolated from each other.

• Common Color Codes: Phase A (Black/Green or Red/Green); Phase B (Red/Blue or Yellow/Blue) (Note: Standards vary by manufacturer; always verify with a multimeter).
• Direction Reversal: If the motor runs in the wrong direction, swap the two wires of Phase A (A+ ↔ A-) OR the two wires of Phase B (B+ ↔ B-). Do not swap both phases simultaneously.

1. Terminal Mapping:
   • VDC / +V: Connect to DC positive.
   • GND / 0V: Connect to DC negative.
2. Reverse Polarity Warning:
   • DC stepper drivers do not tolerate reverse polarity. Connecting positive and negative backwards will destroy internal electrolytic capacitors and MOSFET H-bridges instantly.
3. Voltage & Power Sizing:
   • Supply Voltage: Higher bus voltage reduces torque fall-off at high speeds. Choose a voltage in the mid-to-high range of the driver's specification (e.g., use 36V–48V for a 24V–50V rated driver).
   • Current Capacity: The rated output current of the power supply should be 1.3~1.5* the combined rated phase currents of all connected motors.

Before powering on, set the DIP switches on the side of the driver:

1. Output Current Setting (SW1 ~ SW3):
   • Match the driver's peak/RMS current to the motor's rated nameplate current. Excessive current causes overheating; insufficient current reduces available torque.
2. Standstill Current Reduction (SW4):
   • Half Current Mode (Recommended): Automatically halves output current ~200 ms after movement stops, cutting idle heat dissipation by over 50%.
   • Full Current Mode: Maintains 100% holding torque at zero speed (only needed for vertical anti-drop axes without mechanical brakes).
3. Microstepping Resolution (SW5 ~ SW8):
   • Higher microstepping smooths low-speed rotation and suppresses acoustic resonance. Common recommended settings: 8 microsteps (1600 pulses/rev) or 16 microsteps (3200 pulses/rev).

• Issue 1: Motor does not turn, shaft spins freely with no holding torque
  • Fix: Check the driver's power LED. Inspect the ENA terminal (leaving ENA unconnected enables the motor by default; applying signal releases the shaft).
• Issue 2: Motor locks up, hums/vibrates, but fails to step
  • Fix: Phase A and Phase B leads are mixed up, disrupting the rotating magnetic field; or initial pulse frequency exceeds the motor's pull-in starting frequency (acceleration ramp required).
• Issue 3: Rotation direction is reversed or erratic
  • Fix: Loose DIR signal connection or incorrect common anode/cathode logic level; swap A+ and A- leads.
• Issue 4: Motor loses steps or stalls under load/at high speeds
  • Fix: Unshielded signal cables picking up EMI; bus voltage too low; or DIP switch current set below motor rated capacity.