The MD3 from US Digital combines a microstepping stepper motor driver and a programmable motion controller in a single compact unit. Housed in a black anodized aluminum case measuring 76 × 76 × 26.4 mm, it drives NEMA 14 through 42 stepper motors at up to 7 A peak phase current from a 9–50 VDC supply.

What control modes does the MD3 support?

The MD3 accepts traditional step/direction and go-stop/direction external inputs at up to 250 kHz, or it can execute internally stored profile moves with programmable acceleration, speed, and step count. A jog mode, configurable home cycle with encoder index support, and auto-home on startup are built in. A dedicated brushed DC motor PWM speed control mode extends the driver to non-stepper applications.

How does MODBUS networking work across multiple MD3 units?

An RS485 port with MODBUS RTU protocol allows up to 247 individually addressed MD3 units to share a single communication bus. All motion parameters — including microstep resolution from 2 to 256 microsteps, phase current, acceleration profiles, and move commands — are programmable over the network. Free MD3 Setup and Demo GUI programs handle configuration without writing custom MODBUS code.

What environmental and electrical protections are included?

Rated for -25 to +70 °C ambient operation, the MD3 includes built-in thermal shutdown, ±8 kV ESD protection per IEC 61000-4-2, and a low-power standby mode drawing under 55 mA with the motor disabled. An optional current cutback mode reduces holding current when the motor is idle, lowering heat buildup without losing position.