NOTE: It assumes that you have already installed the SDK.

Make py file

• Create a new Python source file Open it with your editor.

  $ touch tutorial_step1.py
  

Check the Port Names

• Before running the code, check the port name of the connected Dynamixel.
• For General
  • OpenRB-150: ttyACM0: USB ACM device
  • U2D2: FTDI USB Serial Device converter now attached to ttyUSB0

    $ sudo dmesg | grep tty
    

Source Code Description

from dynamixel_easy_sdk import *

def main():
    connector = Connector("/dev/ttyACM0", 57600)
    motor1 = connector.createMotor(1)

    motor1.disableTorque()
    motor1.setOperatingMode(OperatingMode.POSITION)
    motor1.enableTorque()

    target_position = 500
    motor1.setGoalPosition(target_position)

if __name__ == "__main__":
    main()

Import Library

• Import dynamixel_easy_sdk.

  from dynamixel_easy_sdk import *
  

Create Connector and Motor Object

• Create a Connector object with port name and baud rate to manage the communication.

  def main():
      connector = Connector("/dev/ttyACM0", 57600)
  

• Create a Motor object for each Dynamixel servo you want to control with its ID, using the createMotor method of the Connector class.

      motor1 = connector.createMotor(1)
  

Set Operating Mode to Position Control Mode

• Use the methods provided by the Motor class to control the Dynamixel servo.
• Set the operating mode to position control mode.

      motor1.disableTorque()
      motor1.setOperatingMode(OperatingMode.POSITION)
      motor1.enableTorque()
  

Move Motor to Goal Position

• Move the motor to the goal position that you want.

      target_position = 500
      motor1.setGoalPosition(target_position)
  

Error Handling

• When an error occurs, DxlRuntimeError is raised.
• You can catch this error using a try-except block.

  try:
      motor1.setGoalPosition(target_position)
  except DxlRuntimeError as e:
      print(e)
  

• DxlRuntimeError contains DxlError Enum that provides detailed information about the error.

  try:
      motor1.setGoalPosition(target_position)
  except DxlRuntimeError as e:
      if e.dxl_error == DxlError.EASY_SDK_TORQUE_STATUS_MISMATCH:
          print("Torque is off.")
      elif e.dxl_error == DxlError.EASY_SDK_OPERATING_MODE_MISMATCH:
          print("Operating mode is not position control.")
  

NOTE: It assumes that you have already installed and built the SDK.

Make cpp file

• Create a new C++ source file Open it with your editor.

  $ touch tutorial_step1.cpp
  

Check the Port Names

• Before running the code, check the port name of the connected Dynamixel.
• For General
  • OpenRB-150: ttyACM0: USB ACM device
  • U2D2: FTDI USB Serial Device converter now attached to ttyUSB0

    $ sudo dmesg | grep tty
    

Source Code Description

#include "dynamixel_easy_sdk/dynamixel_easy_sdk.hpp"

int main(){

  dynamixel::Connector connector("/dev/ttyACM0", 57600);
  std::unique_ptr<dynamixel::Motor> motor1 = connector.createMotor(1);

  motor1->disableTorque();
  motor1->setOperatingMode(dynamixel::Motor::OperatingMode::POSITION);
  motor1->enableTorque();

  int target_position = 500;
  motor1->setGoalPosition(target_position);
}

Add Header Files

• Add dynamixel_easy_sdk/dynamixel_easy_sdk.hpp to the top of your CPP file. This class is included in the Dynamixel SDK package.

  #include "dynamixel_easy_sdk/dynamixel_easy_sdk.hpp"
  

Create Connector and Motor Object

• Create a Connector object with port name and baud rate to manage the communication.

  int main(){
    dynamixel::Connector connector("/dev/ttyACM0", 57600);
  

• Create a Motor object for each Dynamixel servo you want to control, using the createMotor method of the Connector class.
• This method takes the motor ID as an argument and returns a unique pointer to a Motor instance. (shared_ptr is also available)

    std::unique_ptr<dynamixel::Motor> motor1 = connector.createMotor(1);
  

• This process throws a DxlRuntimeError if the object creation fails.

Set Operating Mode to Position Control Mode

• Use the methods provided by the Motor class to control the Dynamixel servo.
• Set the operating mode to position control mode.

    motor1->disableTorque();
    motor1->setOperatingMode(dynamixel::Motor::OperatingMode::POSITION);
    motor1->enableTorque();
  

Move Motor to Goal Position

• Move the motor to the goal position that you want.

    int target_position = 500;
    motor1->setGoalPosition(target_position);
  

Error Handling

• To ensure your code is robust, every method that sends a command to the motor returns a Result object that encapsulates errors.
• This object lets you safely check for any communication or device errors before proceeding.

• You can check for communication errors and device(dynamixel) errors using the Result object.

  Example

    auto result_void = motor1->disableTorque(); // type of 'result_void' variable is Result<void, DxlError>
    if (!result_void.isSuccess()) {
      std::cerr << dynamixel::getErrorMessage(result_void.error()) << std::endl;
      return 1;
    }
  

Compile and Run

• You can compile and run the code using the following commands

  $ g++ tutorial_step1.cpp -o tutorial_step1 -l dxl_x64_cpp
  $ ./tutorial_step1
  

Full Source Code With Error Handling

#include "dynamixel_easy_sdk/dynamixel_easy_sdk.hpp"

int main(){
  dynamixel::Connector connector("/dev/ttyACM0", 57600);
  std::unique_ptr<dynamixel::Motor> motor1 = connector.createMotor(1);

  auto result_void = motor1->disableTorque(); // type of 'result_void' variable is Result<void, DxlError>
  if (!result_void.isSuccess()) {
    std::cerr << dynamixel::getErrorMessage(result_void.error()) << std::endl;
    return 1;
  }

  result_void = motor1->setOperatingMode(dynamixel::Motor::OperatingMode::POSITION);
  if (!result_void.isSuccess()) {
    std::cerr << dynamixel::getErrorMessage(result_void.error()) << std::endl;
    return 1;
  }

  result_void = motor1->enableTorque();
  if (!result_void.isSuccess()) {
    std::cerr << dynamixel::getErrorMessage(result_void.error()) << std::endl;
    return 1;
  }

  int target_position = 500;
  result_void = motor1->setGoalPosition(target_position);
  if (!result_void.isSuccess()) {
    std::cerr << dynamixel::getErrorMessage(result_void.error()) << std::endl;
    return 1;
  }
}