EM-314A is a bipolar chopper-type microstepping controller designed for precise stepper motor control. The bipolar drive principle provides high torque utilization with most stepper motors, while microstepping enables smooth and stable operation, particularly at low speeds.
The controller provides seven selectable stepping modes ranging from full step to 1/64 microstepping. This allows the motor control to be optimized for torque, resolution and maximum stepping speed according to the application.
The EM-314A uses synchronized chopper current regulation to control the current in both motor windings. This provides smooth operation and efficient torque production across a wide speed range.
Seven selectable stepping modes are available, from full-step operation up to 1/64 microstepping. Lower microstep ratios provide a higher number of command steps per motor revolution, reducing low-speed vibration and improving movement smoothness.
The integrated auxiliary oscillator enables standalone motor operation without an external pulse generator. Preset speeds can be selected using four digital control inputs.
The oscillator operates across a frequency range of 50–10,000 Hz. Its adjustable acceleration ramp provides smooth transitions between speeds and supports reliable motor starting at higher target frequencies.
The indexing function allows predefined motion sequences to be executed without continuous control from an external PLC or other controller.
Each sequence defines the required speed, direction and movement distance as a number of steps. Sequences are selected and activated through four digital inputs, enabling repeatable positioning and indexing movements.
The digital control inputs use positive logic and accept industrial control signals from 4 V to 30 V. TTL-compatible control signals are also supported by the applicable inputs.
Depending on the installed firmware, the controller can also support analog speed control. Newer firmware versions provide an RS-485 interface using the Modbus RTU protocol.
The RS-485 interface operates in two-wire half-duplex mode. Supported communication speeds are 9600 and 19200 baud.
Modbus RTU can be used for remote control, parameter setting and integration into an automation system. The available Modbus functions and register addresses depend on the installed firmware version and are described in the separate communication instructions.
Parameters are configured digitally using the EM-236 Interface Unit. This enables fast commissioning and accurate parameter adjustment without mechanical trimmers.
Parameter settings can also be copied from one controller to other units, simplifying the commissioning of systems containing several EM-314A controllers.
The EM-314A is suitable for indexing mechanisms, dosing equipment, valve actuators, linear motion systems, conveyor positioning, laboratory equipment and other applications requiring repeatable stepper motor movement.
| Nominal operating voltage | 12–48 VDC |
| Operating voltage range | 10–60 VDC |
| Idle current | approx. 20 mA |
| Motor-current setting range | 0.1–6 A in 0.1 A steps |
| Stepping modes | Full step to 1/64 microstepping, seven modes |
| Auxiliary oscillator frequency | 50–10,000 Hz |
| Frequency accuracy | typ. 0.5% |
| Ramp adjustment | 0.1–5 s from 0 to 10,000 Hz |
| Maximum step frequency | 15 kHz |
| Digital input, on state | 4–30 V |
| Digital input, off state | 0–1 V or open circuit |
| Communication interface | Two-wire half-duplex RS-485 |
| Communication protocol | Modbus RTU |
| Communication speed | 9600 / 19200 baud |
| Operating temperature | 0…+50 °C |
| Dimensions | 87 × 72.5 × 25 mm |
| Weight | 310 g |
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