DYNAMIXEL SDK

C Indirect Address Protocol 2.0

Description

This example writes the goal position and LED value and repeats to read present position and moving status through the indirect data storage, rather than write directly to the their own data storages. The indirect address links between direct and indirect data storages. This makes the Syncread and the Syncwrite function accessible to the items which are far from each other’s address.
Available Dynamixel

All series using protocol 2.0

Sample code

/*
* indirect_address.c
*
*  Created on: 2016. 5. 16.
*      Author: Leon Ryu Woon Jung
*/

//
// *********     Indirect Address Example      *********
//
//
// Available Dynamixel model on this example : All models using Protocol 2.0
// This example is designed for using a Dynamixel PRO 54-200, and an USB2DYNAMIXEL.
// To use another Dynamixel model, such as X series, see their details in E-Manual(support.robotis.com) and edit below "#define"d variables yourself.
// Be sure that Dynamixel PRO properties are already set as %% ID : 1 / Baudnum : 3 (Baudrate : 1000000 [1M])
//

#ifdef __linux__
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#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                                            // Control table address is different in Dynamixel model
#define ADDR_PRO_INDIRECTADDRESS_FOR_WRITE      49                  // EEPROM region
#define ADDR_PRO_INDIRECTADDRESS_FOR_READ       59                  // EEPROM region
#define ADDR_PRO_TORQUE_ENABLE                  562
#define ADDR_PRO_LED_RED                        563
#define ADDR_PRO_GOAL_POSITION                  596
#define ADDR_PRO_MOVING                         610
#define ADDR_PRO_PRESENT_POSITION               611
#define ADDR_PRO_INDIRECTDATA_FOR_WRITE         634
#define ADDR_PRO_INDIRECTDATA_FOR_READ          639

// Data Byte Length
#define LEN_PRO_LED_RED                         1
#define LEN_PRO_GOAL_POSITION                   4
#define LEN_PRO_MOVING                          1
#define LEN_PRO_PRESENT_POSITION                4
#define LEN_PRO_INDIRECTDATA_FOR_WRITE          5
#define LEN_PRO_INDIRECTDATA_FOR_READ           5

// 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                                1000000
#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 DXL_MINIMUM_POSITION_VALUE              -150000             // Dynamixel will rotate between this value
#define DXL_MAXIMUM_POSITION_VALUE              150000              // and this value (note that the Dynamixel would not move when the position value is out of movable range. Check e-manual about the range of the Dynamixel you use.)
#define DXL_MINIMUM_LED_VALUE                   0                   // Dynamixel LED will light between this value
#define DXL_MAXIMUM_LED_VALUE                   255                 // and this value
#define DXL_MOVING_STATUS_THRESHOLD             20                  // Dynamixel moving status threshold

#define ESC_ASCII_VALUE                         0x1b

int getch()
{
#ifdef __linux__
  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)
{
#ifdef __linux__
  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
}

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();

  // Initialize Groupsyncwrite instance
  int groupwrite_num = groupSyncWrite(port_num, PROTOCOL_VERSION, ADDR_PRO_INDIRECTDATA_FOR_WRITE, LEN_PRO_INDIRECTDATA_FOR_WRITE);

  // Initialize Groupsyncread instance
  int groupread_num = groupSyncRead(port_num, PROTOCOL_VERSION, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_INDIRECTDATA_FOR_READ);

  int index = 0;
  int dxl_comm_result = COMM_TX_FAIL;             // Communication result
  uint8_t dxl_addparam_result = False;               // AddParam result
  uint8_t dxl_getdata_result = False;                // GetParam result
  int dxl_goal_position[2] = { DXL_MINIMUM_POSITION_VALUE, DXL_MAXIMUM_POSITION_VALUE };         // Goal position

  uint8_t dxl_error = 0;                          // Dynamixel error
  uint8_t dxl_moving = 0;                         // Dynamixel moving status
  uint8_t dxl_led_value[2] = { 0x00, 0xFF };      // Dynamixel LED value
  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;
  }

  // Disable Dynamixel Torque :
  // Indirect address would not accessible when the torque is already enabled
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }
  else
  {
    printf("DXL has been successfully connected \n");
  }

  // INDIRECTDATA parameter storages replace LED, goal position, present position and moving status storages
  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 0, ADDR_PRO_GOAL_POSITION + 0);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 2, ADDR_PRO_GOAL_POSITION + 1);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 4, ADDR_PRO_GOAL_POSITION + 2);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 6, ADDR_PRO_GOAL_POSITION + 3);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 8, ADDR_PRO_LED_RED);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 0, ADDR_PRO_PRESENT_POSITION + 0);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 2, ADDR_PRO_PRESENT_POSITION + 1);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 4, ADDR_PRO_PRESENT_POSITION + 2);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 6, ADDR_PRO_PRESENT_POSITION + 3);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 8, ADDR_PRO_MOVING);
  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);
  }

  // Enable DXL Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }

  // Add parameter storage for the present position value
  dxl_addparam_result = groupSyncReadAddParam(groupread_num, DXL_ID);
  if (dxl_addparam_result != True)
  {
    fprintf(stderr, "[ID:%03d] groupSyncRead addparam failed\n", DXL_ID);
    return 0;
  }

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

    // Add values to the Syncwrite storage
    dxl_addparam_result = groupSyncWriteAddParam(groupwrite_num, DXL_ID, dxl_goal_position[index], 4);
    if (dxl_addparam_result != True)
    {
      fprintf(stderr, "[ID:%03d] groupSyncWrite addparam failed\n", DXL_ID);
      return 0;
    }
    dxl_addparam_result = groupSyncWriteAddParam(groupwrite_num, DXL_ID, dxl_led_value[index], 1);
    if (dxl_addparam_result != True)
    {
      fprintf(stderr, "[ID:%03d] groupSyncWrite addparam failed\n", DXL_ID);
      return 0;
    }

    // Syncwrite all
    groupSyncWriteTxPacket(groupwrite_num);
    if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);

    // Clear syncwrite parameter storage
    groupSyncWriteClearParam(groupwrite_num);

    do
    {
      // Syncread present position from indirectdata2
      groupSyncReadTxRxPacket(groupread_num);
      if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
        printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);

      // Check if groupsyncread data of Dyanamixel is available
      dxl_getdata_result = groupSyncReadIsAvailable(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_PRESENT_POSITION);
      if (dxl_getdata_result != True)
      {
        fprintf(stderr, "[ID:%03d] groupSyncRead getdata failed", DXL_ID);
        return 0;
      }

      // Check if groupsyncread data of Dyanamixel is available
      dxl_getdata_result = groupSyncReadIsAvailable(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ + LEN_PRO_PRESENT_POSITION, LEN_PRO_MOVING);
      if (dxl_getdata_result != True)
      {
        fprintf(stderr, "[ID:%03d] groupSyncRead getdata failed", DXL_ID);
        return 0;
      }

      // Get Dynamixel present position value
      dxl_present_position = groupSyncReadGetData(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_PRESENT_POSITION);

      // Get Dynamixel moving status value
      dxl_moving = groupSyncReadGetData(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ + LEN_PRO_PRESENT_POSITION, LEN_PRO_MOVING);

      printf("[ID:%03d] GoalPos:%d  PresPos:%d  IsMoving:%d\n", DXL_ID, dxl_goal_position[index], dxl_present_position, dxl_moving);

    } while (abs(dxl_goal_position[index] - dxl_present_position) > DXL_MOVING_STATUS_THRESHOLD);

    // Change goal position
    if (index == 0)
    {
      index = 1;
    }
    else
    {
      index = 0;
    }
  }

  // Disable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }

  // 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
// Control table address is different in Dynamixel model
#define ADDR_PRO_INDIRECTADDRESS_FOR_WRITE      49                  // EEPROM region
#define ADDR_PRO_INDIRECTADDRESS_FOR_READ       59                  // EEPROM region
#define ADDR_PRO_TORQUE_ENABLE                  562
#define ADDR_PRO_LED_RED                        563
#define ADDR_PRO_GOAL_POSITION                  596
#define ADDR_PRO_MOVING                         610
#define ADDR_PRO_PRESENT_POSITION               611
#define ADDR_PRO_INDIRECTDATA_FOR_WRITE         634
#define ADDR_PRO_INDIRECTDATA_FOR_READ          639

// Data Byte Length
#define LEN_PRO_LED_RED                         1
#define LEN_PRO_GOAL_POSITION                   4
#define LEN_PRO_MOVING                          1
#define LEN_PRO_PRESENT_POSITION                4
#define LEN_PRO_INDIRECTDATA_FOR_WRITE          5
#define LEN_PRO_INDIRECTDATA_FOR_READ           5

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                                1000000
#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 DXL_MINIMUM_POSITION_VALUE              -150000             // Dynamixel will rotate between this value
#define DXL_MAXIMUM_POSITION_VALUE              150000              // and this value (note that the Dynamixel would not move when the position value is out of movable range. Check e-manual about the range of the Dynamixel you use.)
#define DXL_MINIMUM_LED_VALUE                   0                   // Dynamixel LED will light between this value
#define DXL_MAXIMUM_LED_VALUE                   255                 // and this value
#define DXL_MOVING_STATUS_THRESHOLD             20                  // Dynamixel moving status threshold

#define ESC_ASCII_VALUE                         0x1b

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

As the document previously 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.

The example uses Dynamixel DXL_ID connected with the port DEVICENAME.

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.

Dynamixel LED has its own range of value: 1 byte red LED for Dynamixel MX-28 and 1byte each on red, green, blue LED for Dynamixel PRO 54-200.

DXL_MOVING_STATUS_THRESHOLD acts as a criteria for verifying its rotation stopped.

int getch()
{
#ifdef __linux__
  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)
{
#ifdef __linux__
  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. The example codes mainly apply the function getch() rather than the function kbhit() to get information which key has been pressed.

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();

  // Initialize Groupsyncwrite instance
  int groupwrite_num = groupSyncWrite(port_num, PROTOCOL_VERSION, ADDR_PRO_INDIRECTDATA_FOR_WRITE, LEN_PRO_INDIRECTDATA_FOR_WRITE);

  // Initialize Groupsyncread instance
  int groupread_num = groupSyncRead(port_num, PROTOCOL_VERSION, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_INDIRECTDATA_FOR_READ);

  int index = 0;
  int dxl_comm_result = COMM_TX_FAIL;             // Communication result
  uint8_t dxl_addparam_result = False;               // AddParam result
  uint8_t dxl_getdata_result = False;                // GetParam result
  int dxl_goal_position[2] = { DXL_MINIMUM_POSITION_VALUE, DXL_MAXIMUM_POSITION_VALUE };         // Goal position

  uint8_t dxl_error = 0;                          // Dynamixel error
  uint8_t dxl_moving = 0;                         // Dynamixel moving status
  uint8_t dxl_led_value[2] = { 0x00, 0xFF };      // Dynamixel LED value
  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;
  }

  // Disable Dynamixel Torque :
  // Indirect address would not accessible when the torque is already enabled
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }
  else
  {
    printf("DXL has been successfully connected \n");
  }

  // INDIRECTDATA parameter storages replace LED, goal position, present position and moving status storages
  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 0, ADDR_PRO_GOAL_POSITION + 0);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 2, ADDR_PRO_GOAL_POSITION + 1);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 4, ADDR_PRO_GOAL_POSITION + 2);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 6, ADDR_PRO_GOAL_POSITION + 3);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 8, ADDR_PRO_LED_RED);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 0, ADDR_PRO_PRESENT_POSITION + 0);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 2, ADDR_PRO_PRESENT_POSITION + 1);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 4, ADDR_PRO_PRESENT_POSITION + 2);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 6, ADDR_PRO_PRESENT_POSITION + 3);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 8, ADDR_PRO_MOVING);
  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);
  }

  // Enable DXL Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }

  // Add parameter storage for the present position value
  dxl_addparam_result = groupSyncReadAddParam(groupread_num, DXL_ID);
  if (dxl_addparam_result != True)
  {
    fprintf(stderr, "[ID:%03d] groupSyncRead addparam failed\n", DXL_ID);
    return 0;
  }

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

    // Add values to the Syncwrite storage
    dxl_addparam_result = groupSyncWriteAddParam(groupwrite_num, DXL_ID, dxl_goal_position[index], 4);
    if (dxl_addparam_result != True)
    {
      fprintf(stderr, "[ID:%03d] groupSyncWrite addparam failed\n", DXL_ID);
      return 0;
    }
    dxl_addparam_result = groupSyncWriteAddParam(groupwrite_num, DXL_ID, dxl_led_value[index], 1);
    if (dxl_addparam_result != True)
    {
      fprintf(stderr, "[ID:%03d] groupSyncWrite addparam failed\n", DXL_ID);
      return 0;
    }

    // Syncwrite all
    groupSyncWriteTxPacket(groupwrite_num);
    if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);

    // Clear syncwrite parameter storage
    groupSyncWriteClearParam(groupwrite_num);

    do
    {
      // Syncread present position from indirectdata2
      groupSyncReadTxRxPacket(groupread_num);
      if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
        printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);

      // Check if groupsyncread data of Dyanamixel is available
      dxl_getdata_result = groupSyncReadIsAvailable(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_PRESENT_POSITION);
      if (dxl_getdata_result != True)
      {
        fprintf(stderr, "[ID:%03d] groupSyncRead getdata failed", DXL_ID);
        return 0;
      }

      // Check if groupsyncread data of Dyanamixel is available
      dxl_getdata_result = groupSyncReadIsAvailable(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ + LEN_PRO_PRESENT_POSITION, LEN_PRO_MOVING);
      if (dxl_getdata_result != True)
      {
        fprintf(stderr, "[ID:%03d] groupSyncRead getdata failed", DXL_ID);
        return 0;
      }

      // Get Dynamixel present position value
      dxl_present_position = groupSyncReadGetData(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_PRESENT_POSITION);

      // Get Dynamixel moving status value
      dxl_moving = groupSyncReadGetData(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ + LEN_PRO_PRESENT_POSITION, LEN_PRO_MOVING);

      printf("[ID:%03d] GoalPos:%d  PresPos:%d  IsMoving:%d\n", DXL_ID, dxl_goal_position[index], dxl_present_position, dxl_moving);

    } while (abs(dxl_goal_position[index] - dxl_present_position) > DXL_MOVING_STATUS_THRESHOLD);

    // Change goal position
    if (index == 0)
    {
      index = 1;
    }
    else
    {
      index = 0;
    }
  }

  // Disable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }

  // 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.

  // Initialize Groupsyncwrite instance
  int group_num = groupSyncWrite(port_num, PROTOCOL_VERSION, ADDR_PRO_INDIRECTDATA_FOR_WRITE, LEN_PRO_INDIRECTDATA_FOR_WRITE);

groupSyncWrite() function initializes grouped parameters used for packet construction and packet storing. The utility functions of sync write deals simultaneously with more than one Dynamixel through #port_num port, building packets by the function which uses PROTOCOL_VERSION, and writing LEN_PRO_INDIRECTDATA_FOR_WRITE bytes of the values on the address ADDR_PRO_INDIRECTDATA_FOR_WRITE.

  // Initialize Groupsyncread Structs for Present Position
  int groupread_num = groupSyncRead(port_num, PROTOCOL_VERSION, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_INDIRECTDATA_FOR_READ);

groupSyncRead() function initializes grouped parameters used for packet construction and packet storing. The utility functions of sync read deals simultaneously with more than one Dynamixel through #port_num port, building packets by the function which uses PROTOCOL_VERSION, and requesting LEN_PRO_INDIRECTDATA_FOR_READ bytes of the values on the address ADDR_PRO_INDIRECTDATA_FOR_READ.

  int index = 0;
  int dxl_comm_result = COMM_TX_FAIL;             // Communication result
  int dxl_addparam_result = false;                // AddParam result
  int dxl_getdata_result = false;                 // GetParam result
  int dxl_goal_position[2] = {DXL_MINIMUM_POSITION_VALUE, DXL_MAXIMUM_POSITION_VALUE};         // Goal position

  uint8_t dxl_error = 0;                          // Dynamixel error
  uint8_t dxl_moving = 0;                         // Dynamixel moving status
  uint8_t dxl_led_value[2] = {DXL_MINIMUM_LED_VALUE, DXL_MAXIMUM_LED_VALUE};        // Dynamixel LED value
  int32_t dxl_present_position = 0;               // Present position

index variable points the direction to where the Dynamixel should be rotated.

dxl_comm_result indicates which error has been occurred during packet communication.

dxl_addparam_result indicates the result of parameter addition used for sync/bulk related functions

dxl_getdata_result indicates the result of data reception used for sync/bulk related functions

dxl_goal_position stores goal points of Dynamixel rotation.

dxl_error shows the internal error in Dynamixel.

dxl_moving views whether the Dynamixel is stopped.

dxl_led_value stores LED values of Dynamixel.

dxl_present_position view where now each Dynamixel 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.

  // Disable Dynamixel Torque :
  // Indirect address would not accessible when the torque is already enabled
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }
  else
  {
    printf("DXL has been successfully connected \n");
  }

Indirect address and Indirect data are particularly applicable to control several items far from each other in control table address simultaenously. Nth Indirect data shows one of the item on the control table that Nth Indirect Address points out, so if you want to see Dynamixel LED RED value through 1st indirect data, change value of 1st Indirect Address to ADDR_PRO_LED_RED value.

However, Dynamixel PRO has Indirect Address items on its EEPROM area. (Please see the E-Manual.) To change them, you must disable the torque at first.

Above write1ByteTxRx() function sends an instruction to the #DXL_ID Dynamixel through the port, writing 1 byte of TORQUE_DISABLE value to ADDR_PRO_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.

  // INDIRECTDATA parameter storages replace LED, goal position, present position and moving status storages
  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 0, ADDR_PRO_GOAL_POSITION + 0);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 2, ADDR_PRO_GOAL_POSITION + 1);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 4, ADDR_PRO_GOAL_POSITION + 2);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 6, ADDR_PRO_GOAL_POSITION + 3);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 8, ADDR_PRO_LED_RED);
  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);
  }

These allocate five target address for writing (ADDR_PRO_GOAL_POSITION + 0, ADDR_PRO_GOAL_POSITION + 1, ADDR_PRO_GOAL_POSITION + 2, ADDR_PRO_GOAL_POSITION + 3 and ADDR_PRO_LED_RED) to the Indirect Addresses(ADDR_PRO_INDIRECTADDRESS_FOR_WRITE + 0 ~ 9) 2 bytes each. Now, you can change goal position value or red LED value by writing 4 byte and 1 byte each on the 1st ~ 4th and 5th Indirect Data item.

  // INDIRECTDATA parameter storages replace LED, goal position, present position and moving status storages
  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 0, ADDR_PRO_PRESENT_POSITION + 0);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 2, ADDR_PRO_PRESENT_POSITION + 1);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 4, ADDR_PRO_PRESENT_POSITION + 2);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 6, ADDR_PRO_PRESENT_POSITION + 3);
  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);
  }

  write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_INDIRECTADDRESS_FOR_READ + 8, ADDR_PRO_MOVING);
  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);
  }

These allocate five target address for writing (ADDR_PRO_PRESENT_POSITION + 0, ADDR_PRO_PRESENT_POSITION + 1, ADDR_PRO_PRESENT_POSITION + 2, ADDR_PRO_PRESENT_POSITION + 3 and ADDR_PRO_MOVING) to the Indirect Addresses(ADDR_PRO_INDIRECTADDRESS_FOR_READ + 0 ~ 9) 2 bytes each. Now, you can get present position value or moving status value by reading 4 byte and 1 byte each on the 6st ~ 9th and 10th Indirect Data item.

  // Enable DXL Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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);
  }

As mentioned in the document, above code enables each Dynamixel`s torque to set their status as being ready to move.

write1ByteTxRx() function sends an instruction to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 1 byte of TORQUE_ENABLE value to ADDR_PRO_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.

  // Add parameter storage for the present position value
  dxl_addparam_result = groupSyncReadAddParam(groupread_num, DXL_ID);
  if (dxl_addparam_result != True)
  {
    fprintf(stderr, "[ID:%03d] groupSyncRead addparam failed\n", DXL_ID);
    return 0;
  }

groupSyncReadAddParam() function stores the Dynamixel ID of required data to the syncread target Dynamixel list.

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

    // Add values to the Syncwrite storage
    dxl_addparam_result = groupSyncWriteAddParam(groupwrite_num, DXL_ID, dxl_goal_position[index], 4);
    if (dxl_addparam_result != True)
    {
      fprintf(stderr, "[ID:%03d] groupSyncWrite addparam failed\n", DXL_ID);
      return 0;
    }
    dxl_addparam_result = groupSyncWriteAddParam(groupwrite_num, DXL_ID, dxl_led_value[index], 1);
    if (dxl_addparam_result != True)
    {
      fprintf(stderr, "[ID:%03d] groupSyncWrite addparam failed\n", DXL_ID);
      return 0;
    }

    // Syncwrite all
    groupSyncWriteTxPacket(groupwrite_num);
    if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);

    // Clear syncwrite parameter storage
    groupSyncWriteClearParam(groupwrite_num);

    do
    {
      // Syncread present position from indirectdata2
      groupSyncReadTxRxPacket(groupread_num);
      if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
        printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);

      // Check if groupsyncread data of Dyanamixel is available
      dxl_getdata_result = groupSyncReadIsAvailable(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_PRESENT_POSITION);
      if (dxl_getdata_result != True)
      {
        fprintf(stderr, "[ID:%03d] groupSyncRead getdata failed", DXL_ID);
        return 0;
      }

      // Check if groupsyncread data of Dyanamixel is available
      dxl_getdata_result = groupSyncReadIsAvailable(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ + LEN_PRO_PRESENT_POSITION, LEN_PRO_MOVING);
      if (dxl_getdata_result != True)
      {
        fprintf(stderr, "[ID:%03d] groupSyncRead getdata failed", DXL_ID);
        return 0;
      }

      // Get Dynamixel present position value
      dxl_present_position = groupSyncReadGetData(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ, LEN_PRO_PRESENT_POSITION);

      // Get Dynamixel moving status value
      dxl_moving = groupSyncReadGetData(groupread_num, DXL_ID, ADDR_PRO_INDIRECTDATA_FOR_READ + LEN_PRO_PRESENT_POSITION, LEN_PRO_MOVING);

      printf("[ID:%03d] GoalPos:%d  PresPos:%d  IsMoving:%d\n", DXL_ID, dxl_goal_position[index], dxl_present_position, dxl_moving);

    } while (abs(dxl_goal_position[index] - dxl_present_position) > DXL_MOVING_STATUS_THRESHOLD);

    // Change goal position
    if (index == 0)
    {
      index = 1;
    }
    else
    {
      index = 0;
    }
  }

During while() loop, the controller writes and reads each Dynamixel position through packet transmission/reception(Tx/Rx).

To continue their rotation, press any key except ESC.

groupSyncWriteAddParam() function stores the Dynamixel ID and its goal position dxl_goal_position and LED value dxl_led_value to the syncwrite target Dynamixel list.

groupSyncWriteTxPacket() function sends an instruction to the Dynamixel #DXL_ID through the port, making it possible to write same pre-listed length bytes to same pre-listed address. The function checks Tx/Rx result. getLastTxRxResult() function get it, and then printTxRxResult() function shows result on the console window if any communication error has been occurred.

groupSyncWriteClearParam() function clears the Dynamixel list of groupsyncwrite.

groupSyncReadTxRxPacket() function sends an instruction to the Dynamixel #DXL_ID through #port_num port, making it possible to read same pre-listed length(LEN_PRO_INDIRECTDATA_FOR_READ) of bytes to same pre-listed address(ADDR_PRO_INDIRECTDATA_FOR_READ). The function checks Tx/Rx result. getLastTxRxResult() function gets it, and then printTxRxResult() function shows result on the console window if any communication error has been occurred.

groupSyncReadIsAvailable() function checks if available data is in the groupsyncread data storage. The function returns false if no data is available in the storage.

groupSyncReadGetData() function pop the data received by groupSyncReadTxRxPacket() function out. In the example, it stores LEN_PRO_PRESENT_POSITION byte data and LEN_PRO_MOVING byte data got from ADDR_PRO_INDIRECTDATA_FOR_READ address of Dynamixel.

groupSyncReadClearParam() function clears the Dynamixel list of groupsyncread.

Reading their present position will be ended when absolute value of (dxl_goal_position[index] - dxl_present_position) becomes smaller then DXL_MOVING_STATUS_THRESHOLD.

At last, it changes their direction to the counter-wise and waits for extra key input.

  // Disable Dynamixel Torque
  write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_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 sends an instruction to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 1 byte of TORQUE_DISABLE value to ADDR_PRO_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.

  // Close port
  closePort(port_num);

  return 0;

Finally, port becomes disposed.