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Programmable stepper motor controller SMSD-4.2Modbus

Programmable stepper motor controller SMSD‑4.2Modbus 

Voltage 12 - 48 VDC
Max. current per phase 1 - 4.2 A
Microstepping 1/1 - 1/256
Control methods program, potentiometer, STEP/DIR
Interfaces USB, RS-485 (Modbus ASCII/RTU)

SMSD-4.2Modbus is a programmable stepper motor controller with extended functionality. The device can be controlled from a PLC using the Modbus RTU/ASCII protocol, and also work autonomously according to a user program. The controller provides microstepping 1/1 to 1/256. The morphing function provides a smooth transition from microstepping mode to full-step mode at a given speed, thereby maintaining torque at high speeds. Overheating protection is provided. The controllers are able to work in real time and can be used both to build local automation units and distributed I/O systems with data exchange via RS-485 interface with Modbus protocol.

technical data

Technical data

Interfaces USB, RS-485
Communication protocol Modbus RTU, ASCII
Programming languages LD – ladder diagrams (when use with special software),
IL – instruction list
Max. length of a main user program 28912 instructions
Max. length of a service program 1926 instruction
Minimum processing time for one basic instruction 20 µs
Logic I/O
Logic inputs 8 logic inputs:
  • 2 fast inputs (> 70 nsec)
  • 6 general inputs ( > 5 mks)
Logic outputs 10 logic outputs:
  • 8 transistor type
  • 2 relay type
Logic inputs setting voltage 2.4 VDC
Logic inputs reset voltage 0.7 VDC
Max voltage of logic output of transistor type 80 VDC
Load capacity of the logic output of the transistor type 50 mA
Max voltage of logic output of relay type 350 VAC/VDC
Load capacity of the logic output of the relay type 250 (AC) / 120 (DC) mA
PWM signal generation frequency 0.3 – 50000 Hz
Control modes

Control modes of stepper motor controller SMSD‑4.2Modbus

SMSD‑4.2Modbus provides the following control modes:

  • Program mode -
    this mode is designated for autonomous operation according to a given user program and for direct control of a stepper motor using the Modbus protocol. The controller can be pre-programmed similarly to general industrial PLC. The software for adjusting of the device, user programs assembling and motor control is offered free of charge. SMSD‑4.2Modbus provides the function for debugging of user programs. This function makes it easier to write long and complex operation algorithms and allows finding errors quickly at the stage of user program debugging.
  • Analog speed control mode -
    it is used to set the motor rotation speed with a potentiometer at the front panel of the controller or with external buttons or an encoder.
  • Analog position control mode -
    it is possible with using of a program mode – position of the built-in potentiometer is available to be read and to be used as a position reference during user program executing.
  • Pulse position control STEP/DIR -
    the standard pulse mode for control of "STEP" and "DIRECTION" signals. The stepper motor rotation speed is proportional to the frequency of the STEP signals, the displacement is proportional to the number of pulses of the STEP signal. The direction of rotation depends on the signal level at the DIRECTION (DIR) input.

The motor controller has 8 logic inputs and 10 logic outputs. Their state can be read or set programmatically from a user program (which is loaded into the memory of the device) or by a direct command via the Modbus protocol. The internal program can be assembled, written to the controller and read from it both via the USB port or RS-485. Free software is provided to configure the controller, create and edit internal user programs.

Functions and possibilities

Functions and possibilities of the programmable stepper motor controller SMSD‑4.2Modbus:

  • Communication interfaces are USB and RS-485 are intended for connection to a PC or PLC;
  • Autonomous control of the stepper motor according to the program stored in the controller's memory;
  • Real-time stepper motor control by commands from a computer or PLC via Modbus;
  • Reading and writing the executive user program to the controller's memory via Modbus;
  • Program control of discrete outputs is provided;
  • Pulse position control with standard signals 0/5V "STEP", "DIRECTION" and "ENABLE";
  • Analog speed control is available: using the built-in potentiometer, external buttons or encoder;

Dimensions of the programmable stepper motor controller SMSD‑4.2Modbus

Dimensions of the programmable stepper motor controller SMSD-4.2Modbus