EM-318A is a bipolar chopper-type microstepping controller designed for precise and efficient stepper motor control. The bipolar drive principle provides high torque utilization with most stepper motors, while microstepping enables smooth and quiet operation, particularly at low speeds.
The controller provides seven selectable stepping modes ranging from full step to 1/64 microstepping. This allows motor control to be optimized for torque, resolution and maximum stepping speed according to the application.
The EM-318A 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 more 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 analog input allows the motor stepping frequency to be controlled using a 0–10 V signal. The complete input range corresponds to a pulse-frequency range of 0–10 kHz.
This allows motor speed to be controlled using a potentiometer, PLC analog output or other compatible analog command source.
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.
The input is interpreted as active when its voltage is between 4 V and 30 V. A voltage from 0 V to 1 V, or an open input, is interpreted as inactive.
The RS-485 interface operates in two-wire half-duplex mode using the Modbus RTU protocol. Supported communication speeds are 9600 and 19200 baud.
Modbus RTU can be used for external control, parameter setting and operating-status monitoring. The available functions and register addresses 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-318A controllers.
The EM-318A is suitable for indexing mechanisms, dosing equipment, valve actuators, linear motion systems, conveyor positioning, laboratory equipment and other applications requiring repeatable stepper motor movement.
| Operating voltage | 12–35 VDC |
| Idle current | approx. 20 mA |
| Motor-current setting range | 0.1–3 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 |
| Analog speed input | 0–10 V |
| Analog speed-control range | 0–10 kHz pulse frequency |
| 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 | 100 g |
Ordering larger quantities +100pcs.
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