Step 1: Moving Dynamixel

This tutorial shows you how to move a single Dynamixel using the Dynamixel Easy SDK.

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, baud rate, and protocol version to manage the communication.(Only protocol 2.0 is supported)
```
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/ttyUSB0", 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;
  }
}