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C Clear Multi Turn Protocol 2.0

Sample code

/*
* clear_multi_turn.c
*
*  Created on: 2018. 11. 23.
*      Author: Gilbert Ki Jong Gil
*/

//
// *********     Clear Multi-Turn Example      *********
//
//
// Available Dynamixel model on this example : MX with Protocol 2.0 (firmware v42 or above), Dynamixel X-series (firmware v42 or above)
// This example is designed for using a Dynamixel XM430-W350-R, and an U2D2.
// To use another Dynamixel model, such as MX series, see their details in E-Manual(emanual.robotis.com) and edit below "#define"d variables yourself.
// Be sure that Dynamixel properties are already set as %% ID : 1 / Baudnum : 1 (Baudrate : 57600)
//

#if defined(__linux__) || defined(__APPLE__)
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#define STDIN_FILENO 0
#elif defined(_WIN32) || defined(_WIN64)
#include <conio.h>
#endif

#include <stdlib.h>
#include <stdio.h>
#include "dynamixel_sdk.h"                                  // Uses Dynamixel SDK library

// Control table address
#define ADDR_OPERATING_MODE             11                  // Control table address is different in Dynamixel model
#define ADDR_TORQUE_ENABLE              64
#define ADDR_GOAL_POSITION              116
#define ADDR_PRESENT_POSITION           132

// Protocol version
#define PROTOCOL_VERSION                2.0                 // See which protocol version is used in the Dynamixel

// Default setting
#define DXL_ID                          1                   // Dynamixel ID: 1
#define BAUDRATE                        57600
#define DEVICENAME                      "/dev/ttyUSB0"      // Check which port is being used on your controller
                                                            // ex) Windows: "COM1"   Linux: "/dev/ttyUSB0" Mac: "/dev/tty.usbserial-*"

#define TORQUE_ENABLE                   1                   // Value for enabling the torque
#define TORQUE_DISABLE                  0                   // Value for disabling the torque
#define MAX_POSITION_VALUE              1048575
#define DXL_MOVING_STATUS_THRESHOLD     20                  // Dynamixel moving status threshold
#define EXT_POSITION_CONTROL_MODE       4                   // Value for extended position control mode (operating mode)

#define ESC_ASCII_VALUE                 0x1b
#define SPACE_ASCII_VALUE               0x20

int getch()
{
#if defined(__linux__) || defined(__APPLE__)
  struct termios oldt, newt;
  int ch;
  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  ch = getchar();
  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  return ch;
#elif defined(_WIN32) || defined(_WIN64)
  return _getch();
#endif
}

int kbhit(void)
{
#if defined(__linux__) || defined(__APPLE__)
  struct termios oldt, newt;
  int ch;
  int oldf;

  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
  fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);
  ch = getchar();
  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  fcntl(STDIN_FILENO, F_SETFL, oldf);

  if (ch != EOF)
  {
    ungetc(ch, stdin);
    return 1;
  }

  return 0;
#elif defined(_WIN32) || defined(_WIN64)
  return _kbhit();
#endif
}

void msecSleep(int waitTime)
{
#if defined(__linux__) || defined(__APPLE__)
    usleep(waitTime * 1000);
#elif defined(_WIN32) || defined(_WIN64)
    _sleep(waitTime);
#endif
}

int main()
{
  // Initialize PortHandler Structs
  // Set the port path
  // Get methods and members of PortHandlerLinux or PortHandlerWindows
  int port_num = portHandler(DEVICENAME);

  // Initialize PacketHandler Structs
  packetHandler();

  int dxl_comm_result = COMM_TX_FAIL;             // Communication result

  uint8_t dxl_error = 0;                          // Dynamixel error
  int32_t dxl_present_position = 0;               // Present position

  // Open port
  if (openPort(port_num))
  {
    printf("Succeeded to open the port!\n");
  }
  else
  {
    printf("Failed to open the port!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Set port baudrate
  if (setBaudRate(port_num, BAUDRATE))
  {
    printf("Succeeded to change the baudrate!\n");
  }
  else
  {
    printf("Failed to change the baudrate!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Set operating mode to extended position control mode
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_OPERATING_MODE, EXT_POSITION_CONTROL_MODE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
  }
  else
  {
    printf("Operating mode changed to extended position control mode. \n");
  }

  // Enable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_TORQUE_ENABLE, TORQUE_ENABLE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
  }
  else
  {
    printf("Dynamixel has been successfully connected \n");
  }

  while (1)
  {
    printf("\nPress any key to continue! (or press ESC to quit!)\n");
    if (getch() == ESC_ASCII_VALUE)
      break;

    printf("  Press SPACE key to clear multi-turn information! (or press ESC to stop!)\n");

    // Write goal position
    write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, MAX_POSITION_VALUE);
    if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
    {
      printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
    }
    else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
    {
      printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
    }

    do
    {
      // Read present position
      dxl_present_position = read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRESENT_POSITION);
      if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      {
        printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
      }
      else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
      {
        printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
      }

      printf("  [ID:%03d] GoalPos:%03d  PresPos:%03d\r", DXL_ID, MAX_POSITION_VALUE, dxl_present_position);

      if (kbhit())
      {
        char c = getch();
        if (c == SPACE_ASCII_VALUE)
        {
          printf("\n  Stop & Clear Multi-Turn Information! \n");

          // Write the present position to the goal position to stop moving
          write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, dxl_present_position);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          msecSleep(300);

          // Clear Multi-Turn Information
          clearMultiTurn(port_num, PROTOCOL_VERSION, DXL_ID);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          // Read present position
          dxl_present_position = read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRESENT_POSITION);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          printf("  Present Position has been reset. : %03d \n", dxl_present_position);

          break;
        }
        else if (c == ESC_ASCII_VALUE)
        {
          printf("\n  Stopped!! \n");

          // Write the present position to the goal position to stop moving
          write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, dxl_present_position);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          break;
        }
      }

    } while ((abs(MAX_POSITION_VALUE - dxl_present_position) > DXL_MOVING_STATUS_THRESHOLD));

    printf("\n");
  }

  // Disable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_TORQUE_ENABLE, TORQUE_DISABLE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
  }

  // Close port
  closePort(port_num);

  return 0;
}

Details

#ifdef __linux__
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#elif defined(_WIN32) || defined(_WIN64)
#include <conio.h>
#endif

This source includes above to get key input interruption while the example is running. Actual functions for getting the input is described in a little below.

#include <stdlib.h>

The function abs() is in the example code, and it needs stdlib.h to be included.

#include <stdio.h>

The example shows Dynamixel status in sequence by the function printf(). So here stdio.h is needed.

#include "dynamixel_sdk.h"                                   // Uses Dynamixel SDK library

All libraries of Dynamixel SDK are linked with the header file dynamixel_sdk.h.

// Control table address
#define ADDR_OPERATING_MODE             11                  // Control table address is different in Dynamixel model
#define ADDR_TORQUE_ENABLE              64
#define ADDR_GOAL_POSITION              116
#define ADDR_PRESENT_POSITION           132

Dynamixel series have their own control tables: Addresses and Byte Length in each items. To control one of the items, its address (and length if necessary) is required. Find your requirements in http://emanual.robotis.com/.

// Protocol version
#define PROTOCOL_VERSION                2.0                 // See which protocol version is used in the Dynamixel

Dynamixel uses either or both protocols: Protocol 1.0 and Protocol 2.0. Choose one of the Protocol which is appropriate in the Dynamixel.

// Default setting
#define DXL_ID                          1                   // Dynamixel ID: 1
#define BAUDRATE                        57600
#define DEVICENAME                      "/dev/ttyUSB0"      // Check which port is being used on your controller
                                                            // ex) Windows: "COM1"   Linux: "/dev/ttyUSB0"

#define TORQUE_ENABLE                   1                   // Value for enabling the torque
#define TORQUE_DISABLE                  0                   // Value for disabling the torque
#define MAX_POSITION_VALUE              1048575
#define DXL_MOVING_STATUS_THRESHOLD     20                  // Dynamixel moving status threshold
#define EXT_POSITION_CONTROL_MODE       4                   // Value for extended position control mode (operating mode)

#define ESC_ASCII_VALUE                 0x1b
#define SPACE_ASCII_VALUE               0x20

Here we set some variables to let you freely change them and use them to run the example code.

As the document already said in previous chapter, customize Dynamixel control table items, such as DXL_ID number, communication BAUDRATE, and the DEVICENAME, on your own terms of needs. In particular, BAUDRATE and DEVICENAME have systematical dependencies on your controller, so make clear what kind of communication method you will use.

Dynamixel basically needs the TORQUE_ENABLE to be rotating or give you its internal information. On the other hand, it doesn’t need torque enabled if you get your goal, so finally do TORQUE_DISABLE to prepare to the next sequence.

Since the Dynamixel has its own rotation range, it may shows malfunction if your request on your dynamixel is out of range. For example, Dynamixel MX-28 and Dynamixel PRO 54-200 has its rotatable range as 0 ~ 4028 and -250950 ~ 250950, each.

DXL_MOVING_STATUS_THRESHOLD acts as a criteria for verifying its rotation stopped. EXT_POSITION_CONTROL_MODE acts as a position control Mode.

int getch()
{
#if defined(__linux__) || defined(__APPLE__)
  struct termios oldt, newt;
  int ch;
  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  ch = getchar();
  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  return ch;
#elif defined(_WIN32) || defined(_WIN64)
  return _getch();
#endif
}

int kbhit(void)
{
#if defined(__linux__) || defined(__APPLE__)
  struct termios oldt, newt;
  int ch;
  int oldf;

  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
  fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);
  ch = getchar();
  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  fcntl(STDIN_FILENO, F_SETFL, oldf);

  if (ch != EOF)
  {
    ungetc(ch, stdin);
    return 1;
  }

  return 0;
#elif defined(_WIN32) || defined(_WIN64)
  return _kbhit();
#endif
}

These functions accept the key inputs in terms of example action and time sleep. The example codes mainly apply the function getch() rather than the function kbhit() to get information which key has been pressed.

void msecSleep(int waitTime)
{
#if defined(__linux__) || defined(__APPLE__)
    usleep(waitTime * 1000);
#elif defined(_WIN32) || defined(_WIN64)
    _sleep(waitTime);
#endif
}

msecSleep() function halt the computational process in which this function is used.

int main()
{
  // Initialize PortHandler Structs
  // Set the port path
  // Get methods and members of PortHandlerLinux or PortHandlerWindows
  int port_num = portHandler(DEVICENAME);

  // Initialize PacketHandler Structs
  packetHandler();

  int dxl_comm_result = COMM_TX_FAIL;             // Communication result

  uint8_t dxl_error = 0;                          // Dynamixel error
  int32_t dxl_present_position = 0;               // Present position

  // Open port
  if (openPort(port_num))
  {
    printf("Succeeded to open the port!\n");
  }
  else
  {
    printf("Failed to open the port!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Set port baudrate
  if (setBaudRate(port_num, BAUDRATE))
  {
    printf("Succeeded to change the baudrate!\n");
  }
  else
  {
    printf("Failed to change the baudrate!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Set operating mode to extended position control mode
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_OPERATING_MODE, EXT_POSITION_CONTROL_MODE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
  }
  else
  {
    printf("Operating mode changed to extended position control mode. \n");
  }

  // Enable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_TORQUE_ENABLE, TORQUE_ENABLE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
  }
  else
  {
    printf("Dynamixel has been successfully connected \n");
  }

  while (1)
  {
    printf("\nPress any key to continue! (or press ESC to quit!)\n");
    if (getch() == ESC_ASCII_VALUE)
      break;

    printf("  Press SPACE key to clear multi-turn information! (or press ESC to stop!)\n");

    // Write goal position
    write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, MAX_POSITION_VALUE);
    if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
    {
      printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
    }
    else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
    {
      printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
    }

    do
    {
      // Read present position
      dxl_present_position = read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRESENT_POSITION);
      if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      {
        printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
      }
      else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
      {
        printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
      }

      printf("  [ID:%03d] GoalPos:%03d  PresPos:%03d\r", DXL_ID, MAX_POSITION_VALUE, dxl_present_position);

      if (kbhit())
      {
        char c = getch();
        if (c == SPACE_ASCII_VALUE)
        {
          printf("\n  Stop & Clear Multi-Turn Information! \n");

          // Write the present position to the goal position to stop moving
          write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, dxl_present_position);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          msecSleep(300);

          // Clear Multi-Turn Information
          clearMultiTurn(port_num, PROTOCOL_VERSION, DXL_ID);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          // Read present position
          dxl_present_position = read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRESENT_POSITION);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          printf("  Present Position has been reset. : %03d \n", dxl_present_position);

          break;
        }
        else if (c == ESC_ASCII_VALUE)
        {
          printf("\n  Stopped!! \n");

          // Write the present position to the goal position to stop moving
          write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, dxl_present_position);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          break;
        }
      }

    } while ((abs(MAX_POSITION_VALUE - dxl_present_position) > DXL_MOVING_STATUS_THRESHOLD));

    printf("\n");
  }

  // Disable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_TORQUE_ENABLE, TORQUE_DISABLE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
  }

  // Close port
  closePort(port_num);

  return 0;
}

In main() function, the codes call actual functions for Dynamixel control.

  // Initialize PortHandler Structs
  // Set the port path
  // Get methods and members of PortHandlerLinux or PortHandlerWindows
  int port_num = portHandler(DEVICENAME);

portHandler() function sets port path as DEVICENAME and get port_num, and prepares an appropriate functions for port control in controller OS automatically. port_num would be used in many functions in the body of the code to specify the port for use.

  // Initialize PacketHandler Structs
  packetHandler();

packetHandler() function initializes parameters used for packet construction and packet storing.

  int dxl_comm_result = COMM_TX_FAIL;             // Communication result

  uint8_t dxl_error = 0;                          // Dynamixel error
  int32_t dxl_present_position = 0;               // Present position

dxl_comm_result indicates which error has been occurred during packet communication.

dxl_error shows the internal error in Dynamixel.

dxl_present_position views where now it points out.

  // Open port
  if (openPort(port_num))
  {
      printf("Succeeded to open the port!\n");
  }
  else
  {
      printf("Failed to open the port!\n");
      printf("Press any key to terminate...\n");
      _getch();
      return 0;
  }

First, controller opens #port_num port to do serial communication with the Dynamixel. If it fails to open the port, the example will be terminated.

  // Set port baudrate
  if (setBaudRate(port_num, BAUDRATE))
  {
      printf("Succeeded to change the baudrate!\n");
  }
  else
  {
      printf("Failed to change the baudrate!\n");
      printf("Press any key to terminate...\n");
      _getch();
      return 0;
  }

Secondly, the controller sets the communication BAUDRATE at #port_num port opened previously.

  // Set operating mode to extended position control mode
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_OPERATING_MODE, EXT_POSITION_CONTROL_MODE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
  }
  else
  {
    printf("Operating mode changed to extended position control mode. \n");
  }

The controller sets the operating mode as Extended Position Control Mode(Multi-turn).

  // Enable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_TORQUE_ENABLE, TORQUE_ENABLE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }
  else
  {
    printf("Dynamixel has been successfully connected \n");
  }

As mentioned in the document, above code enables Dynamixel torque to set its status as being ready to move.

write1ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 1 byte of TORQUE_ENABLE value to ADDR_TORQUE_ENABLE address. The function checks Tx/Rx result and receives Hardware error. getLastTxRxResult() function and getLastRxPacketError() function get either, and then printTxRxResult() function and printRxPacketError() function show results on the console window if any communication error or Hardware error has been occurred.

while (1)
  {
    printf("\nPress any key to continue! (or press ESC to quit!)\n");
    if (getch() == ESC_ASCII_VALUE)
      break;

    printf("  Press SPACE key to clear multi-turn information! (or press ESC to stop!)\n");

    // Write goal position
    write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, MAX_POSITION_VALUE);
    if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
    {
      printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
    }
    else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
    {
      printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
    }

    do
    {
      // Read present position
      dxl_present_position = read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRESENT_POSITION);
      if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      {
        printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
      }
      else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
      {
        printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
      }

      printf("  [ID:%03d] GoalPos:%03d  PresPos:%03d\r", DXL_ID, MAX_POSITION_VALUE, dxl_present_position);

      if (kbhit())
      {
        char c = getch();
        if (c == SPACE_ASCII_VALUE)
        {
          printf("\n  Stop & Clear Multi-Turn Information! \n");

          // Write the present position to the goal position to stop moving
          write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, dxl_present_position);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          msecSleep(300);

          // Clear Multi-Turn Information
          clearMultiTurn(port_num, PROTOCOL_VERSION, DXL_ID);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          // Read present position
          dxl_present_position = read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRESENT_POSITION);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          printf("  Present Position has been reset. : %03d \n", dxl_present_position);

          break;
        }
        else if (c == ESC_ASCII_VALUE)
        {
          printf("\n  Stopped!! \n");

          // Write the present position to the goal position to stop moving
          write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_GOAL_POSITION, dxl_present_position);
          if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            printf("%s\n", getTxRxResult(PROTOCOL_VERSION, dxl_comm_result));
          }
          else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            printf("%s\n", getRxPacketError(PROTOCOL_VERSION, dxl_error));
          }

          break;
        }
      }

    } while ((abs(MAX_POSITION_VALUE - dxl_present_position) > DXL_MOVING_STATUS_THRESHOLD));

    printf("\n");
  }

During while() loop, the controller wait to any key input for start while() and writes and reads the Dynamixel position through packet transmission/reception(Tx/Rx).

To continue its rotation, press any key except ESC.

write4ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 4 byte of MAX_POSITION_VALUE value to ADDR_GOAL_POSITION address. The function checks Tx/Rx result and receives Hardware error. getLastTxRxResult() function and getLastRxPacketError() function get either.

read4ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, requesting 4 bytes of value in ADDR_PRESENT_POSITION address. The function checks Tx/Rx result and receives Hardware error. getLastTxRxResult() function and getLastRxPacketError() function get either.

When the space key input, write4ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 4 byte of dxl_present_position value to ADDR_GOAL_POSITION address. The function checks Tx/Rx result and receives Hardware error. getLastTxRxResult() function and getLastRxPacketError() function get either. And then clearMultiTurn() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port.

Reading its present position will be ended when absolute value of (MAX_POSITION_VALUE - dxl_present_position) becomes smaller then DXL_MOVING_STATUS_THRESHOLD.

  // Disable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_TORQUE_ENABLE, TORQUE_DISABLE);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }

The controller frees the Dynamixel to be idle.

write1ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 1 byte of TORQUE_DISABLE value to ADDR_TORQUE_ENABLE address. The function checks Tx/Rx result and receives Hardware error. getLastTxRxResult() function and getLastRxPacketError() function get either.

  // Close port
  closePort(port_num);

  return 0;

Finally, port becomes disposed.