Ya encontré la solución y funciona.
Se los dejo aquí por si alguien le hace falta o le pueda interesar.
Saludos.
			Se los dejo aquí por si alguien le hace falta o le pueda interesar.
Código (cpp) [Seleccionar] 
#pragma once
namespace InterDuinoCPP {
	using namespace System;
	using namespace System::ComponentModel;
	using namespace System::Collections;
	using namespace System::Windows::Forms;
	using namespace System::Data;
	using namespace System::Drawing;
	using namespace System::IO::Ports; // No olvidar.
	using namespace System::Text;
	/// <summary>
	/// Resumen de Form_Principal
	/// </summary>
	public ref class Form_Principal : public System::Windows::Forms::Form
	{
	public:
		Form_Principal(void)
		{
			InitializeComponent();
			//
			//TODO: agregar código de constructor aquí
			//
			// Abrir puerto miestras se ejecuta la aplicación.
			if (!serialPort1->IsOpen)
			{
				try
				{
					serialPort1->Open();
				}
				catch (Exception^ex)
				{
					MessageBox::Show(ex->ToString());
				}
			}
		}
	protected:
		/// <summary>
		/// Limpiar los recursos que se estén utilizando.
		/// </summary>
		~Form_Principal()
		{
			if (components)
			{
				delete components;
			}
		}
	private: System::Windows::Forms::Button^  button_Led_8_ON;
	private: System::Windows::Forms::Button^  button_Led_8_OFF;
	protected:
	protected:
	private: System::Windows::Forms::Label^  label1;
	private: System::Windows::Forms::Button^  button_Led_13_ON;
	private: System::Windows::Forms::Button^  button_Led_13_OFF;
	private: System::Windows::Forms::Label^  label2;
	private: System::Windows::Forms::RichTextBox^  richTextBox_Mensajes;
	private: System::Windows::Forms::Label^  label3;
	private: System::IO::Ports::SerialPort^  serialPort1;
	private: System::ComponentModel::IContainer^  components;
	private:
		/// <summary>
		/// Variable del diseñador requerida.
		/// </summary>
#pragma region Windows Form Designer generated code
		/// <summary>
		/// Método necesario para admitir el Diseñador. No se puede modificar
		/// el contenido del método con el editor de código.
		/// </summary>
		void InitializeComponent(void)
		{
			this->components = (gcnew System::ComponentModel::Container());
			this->button_Led_8_ON = (gcnew System::Windows::Forms::Button());
			this->button_Led_8_OFF = (gcnew System::Windows::Forms::Button());
			this->label1 = (gcnew System::Windows::Forms::Label());
			this->button_Led_13_ON = (gcnew System::Windows::Forms::Button());
			this->button_Led_13_OFF = (gcnew System::Windows::Forms::Button());
			this->label2 = (gcnew System::Windows::Forms::Label());
			this->richTextBox_Mensajes = (gcnew System::Windows::Forms::RichTextBox());
			this->label3 = (gcnew System::Windows::Forms::Label());
			this->serialPort1 = (gcnew System::IO::Ports::SerialPort(this->components));
			this->SuspendLayout();
			// 
			// button_Led_8_ON
			// 
			this->button_Led_8_ON->Location = System::Drawing::Point(43, 37);
			this->button_Led_8_ON->Name = L"button_Led_8_ON";
			this->button_Led_8_ON->Size = System::Drawing::Size(75, 23);
			this->button_Led_8_ON->TabIndex = 0;
			this->button_Led_8_ON->Text = L"ON";
			this->button_Led_8_ON->UseVisualStyleBackColor = true;
			this->button_Led_8_ON->Click += gcnew System::EventHandler(this, &Form_Principal::button_Led_8_ON_Click);
			// 
			// button_Led_8_OFF
			// 
			this->button_Led_8_OFF->Location = System::Drawing::Point(43, 77);
			this->button_Led_8_OFF->Name = L"button_Led_8_OFF";
			this->button_Led_8_OFF->Size = System::Drawing::Size(75, 23);
			this->button_Led_8_OFF->TabIndex = 1;
			this->button_Led_8_OFF->Text = L"OFF";
			this->button_Led_8_OFF->UseVisualStyleBackColor = true;
			this->button_Led_8_OFF->Click += gcnew System::EventHandler(this, &Form_Principal::button_Led_8_OFF_Click);
			// 
			// label1
			// 
			this->label1->AutoSize = true;
			this->label1->Location = System::Drawing::Point(62, 21);
			this->label1->Name = L"label1";
			this->label1->Size = System::Drawing::Size(34, 13);
			this->label1->TabIndex = 2;
			this->label1->Text = L"Led 8";
			// 
			// button_Led_13_ON
			// 
			this->button_Led_13_ON->Location = System::Drawing::Point(166, 37);
			this->button_Led_13_ON->Name = L"button_Led_13_ON";
			this->button_Led_13_ON->Size = System::Drawing::Size(75, 23);
			this->button_Led_13_ON->TabIndex = 3;
			this->button_Led_13_ON->Text = L"ON";
			this->button_Led_13_ON->UseVisualStyleBackColor = true;
			this->button_Led_13_ON->Click += gcnew System::EventHandler(this, &Form_Principal::button_Led_13_ON_Click);
			// 
			// button_Led_13_OFF
			// 
			this->button_Led_13_OFF->Location = System::Drawing::Point(166, 77);
			this->button_Led_13_OFF->Name = L"button_Led_13_OFF";
			this->button_Led_13_OFF->Size = System::Drawing::Size(75, 23);
			this->button_Led_13_OFF->TabIndex = 4;
			this->button_Led_13_OFF->Text = L"OFF";
			this->button_Led_13_OFF->UseVisualStyleBackColor = true;
			this->button_Led_13_OFF->Click += gcnew System::EventHandler(this, &Form_Principal::button_Led_13_OFF_Click);
			// 
			// label2
			// 
			this->label2->AutoSize = true;
			this->label2->Location = System::Drawing::Point(186, 21);
			this->label2->Name = L"label2";
			this->label2->Size = System::Drawing::Size(40, 13);
			this->label2->TabIndex = 5;
			this->label2->Text = L"Led 13";
			// 
			// richTextBox_Mensajes
			// 
			this->richTextBox_Mensajes->Dock = System::Windows::Forms::DockStyle::Bottom;
			this->richTextBox_Mensajes->Location = System::Drawing::Point(0, 129);
			this->richTextBox_Mensajes->Name = L"richTextBox_Mensajes";
			this->richTextBox_Mensajes->Size = System::Drawing::Size(284, 133);
			this->richTextBox_Mensajes->TabIndex = 6;
			this->richTextBox_Mensajes->Text = L"";
			// 
			// label3
			// 
			this->label3->AutoSize = true;
			this->label3->Location = System::Drawing::Point(12, 113);
			this->label3->Name = L"label3";
			this->label3->Size = System::Drawing::Size(121, 13);
			this->label3->TabIndex = 7;
			this->label3->Text = L"Mensaje desde Arduino:";
			// 
			// serialPort1
			// 
			this->serialPort1->BaudRate = 115200;
			this->serialPort1->PortName = L"COM4";
			this->serialPort1->DataReceived += gcnew System::IO::Ports::SerialDataReceivedEventHandler(this, &Form_Principal::serialPort1_DataReceived);
			// 
			// Form_Principal
			// 
			this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
			this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
			this->ClientSize = System::Drawing::Size(284, 262);
			this->Controls->Add(this->label3);
			this->Controls->Add(this->richTextBox_Mensajes);
			this->Controls->Add(this->label2);
			this->Controls->Add(this->button_Led_13_OFF);
			this->Controls->Add(this->button_Led_13_ON);
			this->Controls->Add(this->label1);
			this->Controls->Add(this->button_Led_8_OFF);
			this->Controls->Add(this->button_Led_8_ON);
			this->Name = L"Form_Principal";
			this->StartPosition = System::Windows::Forms::FormStartPosition::CenterScreen;
			this->Text = L"Mini Interfaz C++";
			this->ResumeLayout(false);
			this->PerformLayout();
		}
#pragma endregion
	private: System::Void button_Led_8_ON_Click(System::Object^  sender, System::EventArgs^  e) {
		array<Byte> ^miBuffer = Encoding::ASCII->GetBytes("Led_8_ON");
		serialPort1->Write(miBuffer, 0, miBuffer->Length);
	}
private: System::Void button_Led_8_OFF_Click(System::Object^  sender, System::EventArgs^  e) {
	array<Byte> ^miBuffer = Encoding::ASCII->GetBytes("Led_8_OFF");
	serialPort1->Write(miBuffer, 0, miBuffer->Length);
}
private: System::Void button_Led_13_ON_Click(System::Object^  sender, System::EventArgs^  e) {
	cli::array<unsigned char> ^miBuffer = gcnew cli::array<unsigned char>(9);
	miBuffer[0] = 0x4C; // ASCII letra "L".
	miBuffer[1] = 0x65; // ASCII letra "e".
	miBuffer[2] = 0x64; // ASCII letra "d".
	miBuffer[3] = 0x5F; // ASCII letra "_".
	miBuffer[4] = 0x31; // ASCII letra "1".
	miBuffer[5] = 0x33; // ASCII letra "3".
	miBuffer[6] = 0x5F; // ASCII letra "_".
	miBuffer[7] = 0x4F; // ASCII letra "O".
	miBuffer[8] = 0x4E; // ASCII letra "N".
	serialPort1->Write(miBuffer, 0, miBuffer->Length);
}
private: System::Void button_Led_13_OFF_Click(System::Object^  sender, System::EventArgs^  e) {
	cli::array<unsigned char> ^miBuffer = gcnew cli::array<unsigned char>(10);
	miBuffer[0] = 0x4C; // ASCII letra "L".
	miBuffer[1] = 0x65; // ASCII letra "e".
	miBuffer[2] = 0x64; // ASCII letra "d".
	miBuffer[3] = 0x5F; // ASCII letra "_".
	miBuffer[4] = 0x31; // ASCII letra "1".
	miBuffer[5] = 0x33; // ASCII letra "3".
	miBuffer[6] = 0x5F; // ASCII letra "_".
	miBuffer[7] = 0x4F; // ASCII letra "O".
	miBuffer[8] = 0x46; // ASCII letra "F".
	miBuffer[9] = 0x46; // ASCII letra "F".
	serialPort1->Write(miBuffer, 0, miBuffer->Length);
}
		 // Declaramos un delegado.
		 delegate void Delegado(String ^ Recibidos);
private: Void serialPort1_DataReceived(Object^  sender, SerialDataReceivedEventArgs^  e) {
	// Utilizremos un string como buffer de recepción.
	String ^ Recibidos;
	if (serialPort1->BytesToRead > 0){ // Si hay carácter que leer...
		Recibidos = serialPort1->ReadExisting(); // Acumula los carácteres recibido.
		// Invocamos y cargamos los bytes en rictTextBox_Mensajes.
		Delegado ^ Actualizar = gcnew Delegado(this, &Form_Principal::ByteRecibidos);
		this->Invoke(Actualizar, Recibidos);
	}
}
		 void ByteRecibidos(String ^ Data){
			 // Los carácteres almacenado en 'Data' se depositan en richTextBox_Mensaje.
			 richTextBox_Mensajes->Text += Data;
			 // Selecciona la posición final para leer los mensajes entrantes.
			 richTextBox_Mensajes->SelectionStart = richTextBox_Mensajes->Text->Length;
			 // Mantiene el scroll en la entrada de cada mensaje.
			 richTextBox_Mensajes->ScrollToCaret();
		 }
};
}Saludos.



