DYNAMIXEL SDK

CSharp Ping Protocol 2.0

Description

This example tries to ping Dynamixel and shows the model number responded from Dynamixel. The example is commonly used to check for Dynamixel’s connection or to get model number to refer its specification.
Available Dynamixel

All series using protocol 2.0

Sample code

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

//
// *********     Ping 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 ping
{
  class Ping
  {
    // 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 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 dxl_comm_result = COMM_TX_FAIL;                                   // Communication result

      byte dxl_error = 0;                                                   // Dynamixel error
      UInt16 dxl_model_number;                                              // Dynamixel model number

      // 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;
      }

      // Try to ping the Dynamixel
      // Get Dynamixel model number
      dxl_model_number = dynamixel.pingGetModelNum(port_num, PROTOCOL_VERSION, DXL_ID);
      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}] ping Succeeded. Dynamixel model number : {1}", DXL_ID, dxl_model_number);

      // Close port
      dynamixel.closePort(port_num);

      return;
    }
  }
}

Details

using System;

The functions 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.

// 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"

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.

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 dxl_comm_result = COMM_TX_FAIL;                                   // Communication result

  byte dxl_error = 0;                                                   // Dynamixel error
  UInt16 dxl_model_number;                                              // Dynamixel model number

  // 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;
  }

  // Try to ping the Dynamixel
  // Get Dynamixel model number
  dxl_model_number = dynamixel.pingGetModelNum(port_num, PROTOCOL_VERSION, DXL_ID);
  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}] ping Succeeded. Dynamixel model number : {1}", DXL_ID, dxl_model_number);

  // 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 dxl_comm_result = COMM_TX_FAIL;                                   // Communication result

byte dxl_error = 0;                                                   // Dynamixel error
UInt16 dxl_model_number;                                              // Dynamixel model number

dxl_comm_result indicates which error has been occurred during packet communication.

dxl_error shows the internal error in Dynamixel.

dxl_model_number keeps Dynamixel model number.

// 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.

// Try to ping the Dynamixel
// Get Dynamixel model number
dxl_model_number = dynamixel.pingGetModelNum(port_num, PROTOCOL_VERSION, DXL_ID);
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);
}

pingGetModelNum() function sends an instruction to the #DXL_ID Dynamixel through #port_num port. Then, it receives the dxl_model_number. 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.