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Sample Code

CSharp Protocol 2.0

CSharp Read Write Protocol 2.0

Sample code

/*
 * ReadWrite.cs
 *
 *  Created on: 2016. 6. 20.
 *      Author: Ryu Woon Jung (Leon)
 */

//
// *********     Read and Write 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 variables yourself.
// Be sure that Dynamixel PRO properties are already set as %% ID : 1 / Baudnum : 3 (Baudrate : 1000000 [1M])
//

using System;
using dynamixel_sdk;

namespace read_write
{
  class ReadWrite
  {
    // Control table address
    public const int ADDR_PRO_TORQUE_ENABLE          = 562;                 // Control table address is different in Dynamixel model
    public const int ADDR_PRO_GOAL_POSITION          = 596;
    public const int ADDR_PRO_PRESENT_POSITION       = 611;

    // Protocol version
    public const int PROTOCOL_VERSION                = 2;                   // See which protocol version is used in the Dynamixel

    // Default setting
    public const int DXL_ID                          = 1;                   // Dynamixel ID: 1
    public const int BAUDRATE                        = 1000000;
    public const string DEVICENAME                   = "/dev/ttyUSB0";      // Check which port is being used on your controller
                                                                            // ex) "COM1"   Linux: "/dev/ttyUSB0"

    public const int TORQUE_ENABLE                   = 1;                   // Value for enabling the torque
    public const int TORQUE_DISABLE                  = 0;                   // Value for disabling the torque
    public const int DXL_MINIMUM_POSITION_VALUE      = -150000;             // Dynamixel will rotate between this value
    public const int 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.)
    public const int DXL_MOVING_STATUS_THRESHOLD     = 20;                  // Dynamixel moving status threshold

    public const byte ESC_ASCII_VALUE                = 0x1b;

    public const int COMM_SUCCESS                    = 0;                   // Communication Success result value
    public const int COMM_TX_FAIL                    = -1001;               // Communication Tx Failed

    static void Main(string[] args)
    {
      // Initialize PortHandler Structs
      // Set the port path
      // Get methods and members of PortHandlerLinux or PortHandlerWindows
      int port_num = dynamixel.portHandler(DEVICENAME);

      // Initialize PacketHandler Structs
      dynamixel.packetHandler();

      int index = 0;
      int dxl_comm_result = COMM_TX_FAIL;                                   // Communication result
      int[] dxl_goal_position = new int[2]{ DXL_MINIMUM_POSITION_VALUE, DXL_MAXIMUM_POSITION_VALUE };         // Goal position

      byte dxl_error = 0;                                                   // Dynamixel error
      Int32 dxl_present_position = 0;                                       // Present position

      // Open port
      if (dynamixel.openPort(port_num))
      {
        Console.WriteLine("Succeeded to open the port!");
      }
      else
      {
        Console.WriteLine("Failed to open the port!");
        Console.WriteLine("Press any key to terminate...");
        Console.ReadKey();
        return;
      }

      // Set port baudrate
      if (dynamixel.setBaudRate(port_num, BAUDRATE))
      {
        Console.WriteLine("Succeeded to change the baudrate!");
      }
      else
      {
        Console.WriteLine("Failed to change the baudrate!");
        Console.WriteLine("Press any key to terminate...");
        Console.ReadKey();
        return;
      }

      // Enable Dynamixel Torque
      dynamixel.write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_TORQUE_ENABLE, TORQUE_ENABLE);
      if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      {
        dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
      }
      else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
      {
        dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
      }
      else
      {
        Console.WriteLine("Dynamixel has been successfully connected");
      }

      while (true)
      {
        Console.WriteLine("Press any key to continue! (or press ESC to quit!)");
        if (Console.ReadKey().KeyChar == ESC_ASCII_VALUE)
          break;

        // Write goal position
        dynamixel.write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_GOAL_POSITION, (UInt32)dxl_goal_position[index]);
        if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
        {
          dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
        }
        else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
        {
          dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
        }

        do
        {
          // Read present position
          dxl_present_position = (Int32)dynamixel.read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_PRESENT_POSITION);
          if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
          {
            dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
          }
          else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
          {
            dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
          }

          Console.WriteLine("[ID: {0}] GoalPos: {1}  PresPos: {2}", DXL_ID, dxl_goal_position[index], dxl_present_position);

        } while ((Math.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
      dynamixel.write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_TORQUE_ENABLE, TORQUE_DISABLE);
      if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      {
        dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
      }
      else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
      {
        dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
      }

      // Close port
      dynamixel.closePort(port_num);

      return;
    }
  }
}

Details

using System;

The functions Math.Abs(), Console.* for I/O, are in the example code, and it uses System namespace.

using dynamixel_sdk;

All libraries of Dynamixel SDK are wrapped into the dynamixel_sdk namespace.

// Control table address
public const int ADDR_PRO_TORQUE_ENABLE          = 562;                 // Control table address is different in Dynamixel model
public const int ADDR_PRO_GOAL_POSITION          = 596;
public const int ADDR_PRO_PRESENT_POSITION       = 611;

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://support.robotis.com/.

// Protocol version
public const int PROTOCOL_VERSION                = 2;                   // 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
public const int DXL_ID                          = 1;                   // Dynamixel ID: 1
public const int BAUDRATE                        = 1000000;
public const string DEVICENAME                   = "/dev/ttyUSB0";      // Check which port is being used on your controller
                                                                        // ex) "COM1"   Linux: "/dev/ttyUSB0"

public const int TORQUE_ENABLE                   = 1;                   // Value for enabling the torque
public const int TORQUE_DISABLE                  = 0;                   // Value for disabling the torque
public const int DXL_MINIMUM_POSITION_VALUE      = -150000;             // Dynamixel will rotate between this value
public const int 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.)
public const int DXL_MOVING_STATUS_THRESHOLD     = 20;                  // Dynamixel moving status threshold

public const byte 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 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.

public const int COMM_SUCCESS                    = 0;                   // Communication Success result value
public const int COMM_TX_FAIL                    = -1001;               // Communication Tx Failed

Each of the variables above show the meaning of the communication result value.

static void Main(string[] args)
{
  // Initialize PortHandler Structs
  // Set the port path
  // Get methods and members of PortHandlerLinux or PortHandlerWindows
  int port_num = dynamixel.portHandler(DEVICENAME);

  // Initialize PacketHandler Structs
  dynamixel.packetHandler();

  int index = 0;
  int dxl_comm_result = COMM_TX_FAIL;                                   // Communication result
  int[] dxl_goal_position = new int[2]{ DXL_MINIMUM_POSITION_VALUE, DXL_MAXIMUM_POSITION_VALUE };         // Goal position

  byte dxl_error = 0;                                                   // Dynamixel error
  Int32 dxl_present_position = 0;                                       // Present position

  // Open port
  if (dynamixel.openPort(port_num))
  {
    Console.WriteLine("Succeeded to open the port!");
  }
  else
  {
    Console.WriteLine("Failed to open the port!");
    Console.WriteLine("Press any key to terminate...");
    Console.ReadKey();
    return;
  }

  // Set port baudrate
  if (dynamixel.setBaudRate(port_num, BAUDRATE))
  {
    Console.WriteLine("Succeeded to change the baudrate!");
  }
  else
  {
    Console.WriteLine("Failed to change the baudrate!");
    Console.WriteLine("Press any key to terminate...");
    Console.ReadKey();
    return;
  }

  // Enable Dynamixel Torque
  dynamixel.write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_TORQUE_ENABLE, TORQUE_ENABLE);
  if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }
  else
  {
    Console.WriteLine("Dynamixel has been successfully connected");
  }

  while (true)
  {
    Console.WriteLine("Press any key to continue! (or press ESC to quit!)");
    if (Console.ReadKey().KeyChar == ESC_ASCII_VALUE)
      break;

    // Write goal position
    dynamixel.write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_GOAL_POSITION, (UInt32)dxl_goal_position[index]);
    if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
    {
      dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
    }
    else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
    {
      dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
    }

    do
    {
      // Read present position
      dxl_present_position = (Int32)dynamixel.read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_PRESENT_POSITION);
      if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
      {
        dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
      }
      else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
      {
        dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
      }

      Console.WriteLine("[ID: {0}] GoalPos: {1}  PresPos: {2}", DXL_ID, dxl_goal_position[index], dxl_present_position);

    } while ((Math.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
  dynamixel.write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_TORQUE_ENABLE, TORQUE_DISABLE);
  if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }

  // Close port
  dynamixel.closePort(port_num);

  return;
}

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 = dynamixel.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
dynamixel.packetHandler();

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

int index = 0;
int dxl_comm_result = COMM_TX_FAIL;                                   // Communication result
int[] dxl_goal_position = new int[2]{ DXL_MINIMUM_POSITION_VALUE, DXL_MAXIMUM_POSITION_VALUE };         // Goal position

byte dxl_error = 0;                                                   // Dynamixel error
Int32 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_goal_position stores goal points of Dynamixel rotation.

dxl_error shows the internal error in Dynamixel.

dxl_present_position views where now it points out.

// Open port
if (dynamixel.openPort(port_num))
{
  Console.WriteLine("Succeeded to open the port!");
}
else
{
  Console.WriteLine("Failed to open the port!");
  Console.WriteLine("Press any key to terminate...");
  Console.ReadKey();
  return;
}

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 (dynamixel.setBaudRate(port_num, BAUDRATE))
{
  Console.WriteLine("Succeeded to change the baudrate!");
}
else
{
  Console.WriteLine("Failed to change the baudrate!");
  Console.WriteLine("Press any key to terminate...");
  Console.ReadKey();
  return;
}

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

// Enable Dynamixel Torque
dynamixel.write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_TORQUE_ENABLE, TORQUE_ENABLE);
if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
{
  dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
}
else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
{
  dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
}
else
{
  Console.WriteLine("Dynamixel has been successfully connected");
}

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_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.

while (true)
{
  Console.WriteLine("Press any key to continue! (or press ESC to quit!)");
  if (Console.ReadKey().KeyChar == ESC_ASCII_VALUE)
    break;

  // Write goal position
  dynamixel.write4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_GOAL_POSITION, (UInt32)dxl_goal_position[index]);
  if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }

  do
  {
    // Read present position
    dxl_present_position = (Int32)dynamixel.read4ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_PRESENT_POSITION);
    if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
    {
      dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
    }
    else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
    {
      dynamixel.printRxPacketError(PROTOCOL_VERSION, dxl_error);
    }

    Console.WriteLine("[ID: {0}] GoalPos: {1}  PresPos: {2}", DXL_ID, dxl_goal_position[index], dxl_present_position);

  } while ((Math.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 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 dxl_goal_position[index] value to ADDR_PRO_GOAL_POSITION 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.

read4ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, requesting 4 bytes of value in ADDR_PRO_PRESENT_POSITION 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.

Reading its 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 its direction to the counter-wise and waits for extra key input.

// Disable Dynamixel Torque
dynamixel.write1ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, ADDR_PRO_TORQUE_ENABLE, TORQUE_DISABLE);
if ((dxl_comm_result = dynamixel.getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
{
  dynamixel.printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
}
else if ((dxl_error = dynamixel.getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
{
  dynamixel.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_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
dynamixel.closePort(port_num);

return;

Finally, port becomes disposed.