Socket Client

using System;

using System.Net;

using System.Net.Sockets;

// This C# "Console Application" example program demonstrates SCPI

// communication with an Keysight TCP socket-enabled instrument that

// supports socket "control connections" (such as VNA network analyzers,

// which have support for control connections in their socket

// implementation as of VNA Firmware A.08.33.01).

namespace CSharpSocketClient

{

  /// <summary>

  /// The class supporting the main entry point for the application.

  /// </summary>

  class MainClass

  {

   static AsyncCallback m_pCallbackFunc;

   static string m_AsyncReply;

   /// <summary>

   /// The main entry point for the application.

   /// </summary>

   [STAThread]

   static int Main(string[] args)

   {

     try

     {

      if (args.Length != 1)

      {

        Console.WriteLine("");

        Console.WriteLine("Usage -- with Microsoft's .NET runtime:");

        Console.WriteLine("SocketClient servernameoraddress");

        Console.WriteLine("Example: SocketClient 192.168.0.1");

        Console.WriteLine("");

        Console.WriteLine("Usage -- with Mono's (www.mono-project.com) .NET runtime:");

        Console.WriteLine("mono SocketClient.exe servernameoraddress");

        Console.WriteLine("Example: mono SocketClient.exe 192.168.0.1");

        return 1;

      }

      string server = args[0];

      Int32 port = 5025; // default socket port number for the VNA

      // Create the primary client socket instance

      Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

      // Get the DNS IP addresses associated with the instrument.

      // (if 'server' string contains the IP address rather than DNS name, this still works)

      IPHostEntry hostInfo = Dns.Resolve(server);

      IPAddress[] IPaddresses = hostInfo.AddressList;

      if (IPaddresses.GetLength(0) < 1)

        return 1;

      // Create an endpoint to use for opening the socket connection

      IPEndPoint endpoint1 = new IPEndPoint (IPaddresses[0], port);

      // Open the connection to the server instrument

      client.Connect(endpoint1);

      if(!client.Connected)

        return 1;

      // Query the instrument's ID string.

      string id = Parse(client, "*IDN?");

      // Clear the instrument's Status Byte

      Parse(client, "*CLS");

      // Enable for the OPC bit (bit 0, which has weight 1) in the instrument's

      // Event Status Register, so that when that bit's value transitions from 0 to 1

      // then the Event Status Register bit in the Status Byte (bit 5 of that byte)

      // will become set.

      Parse(client, "*ESE 1");

      // Enable for bit 5 (which has weight 32) in the Status Byte to generate an

      // SRQ when that bit's value transitions from 0 to 1.

      Parse(client, "*SRE 32");

      // Ask the instrument for the number of a port on which a 'control'

      // socket connection can be opened.

      string controlPortNumStr = Parse(client, "SYSTem:COMMunicate:TCPip:CONTrol?");

      Int32 controlPortNum = System.Convert.ToInt32(controlPortNumStr);

      // Create the client "control connection" socket instance

      Socket controlClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

      // Create an endpoint to use for opening the control connection

      IPEndPoint endpoint2 = new IPEndPoint (IPaddresses[0], controlPortNum);

      // Connect to the server instrument via the port number that was returned by the instrument.

      controlClient.Connect(endpoint2);

      if(!controlClient.Connected)

        return 1;

      // Start the control connection listening for an SRQ message.

      BeginListeningForAsyncReply(controlClient);

      // Now send a preset command to the instrument, accompanied by '*OPC' such

      // that when that operation is complete an SRQ event will be generated

      // which posts the Status Byte message on the control connection.

      Parse(client, "SYSTem:PRESet;*OPC");

      // Normally at this point you would want to have your program do other things

      // right here until the SRQ callback occurs, instead of just idling here waiting

      // for it.

      do {} while (m_AsyncReply == null);

      // Now that the SRQ has occurred, we can issue a Device Clear via the control connection.

      Parse(controlClient, "DCL");

      // The instrument will respond back with "DCL" (and linefeed character appended

      // on the end) via the control connection when it has finished processing the

      // Device Clear request. Note that this 'Response' method uses the synchronous

      // form of 'Receive', so it could potentially time out if the instrument were

      // to take a long time to process the Device Clear. So alternatively the

      // 'BeginListeningForAsyncReply' could be used for this instead of 'Response'.

      string deviceClearResponse = Response(controlClient);

      // Close both of the socket client sessions.

      controlClient.Close();

      client.Close();

     }

     catch (ArgumentNullException e)

     {

      Console.WriteLine("ArgumentNullException: {0}", e);

     }

     catch (SocketException e)

     {

      Console.WriteLine("SocketException: {0}", e);

     }

     Console.WriteLine("/n Press Enter to continue...");

     Console.Read();

     return 0;

   }

   static string Parse(Socket client, string command)

   {

     // Translate the passed command into ASCII and store it as a Byte array.

     Byte[] data = System.Text.Encoding.ASCII.GetBytes(command);   

     // Send the command to the socket-enabled instrument.

     client.Send(data);

     // Has to be followed by a linefeed character as terminator.

     Byte[] lf = {(Byte)'/n'};

     client.Send(lf);

     Console.WriteLine("Sent: {0}", command);   

     // If the message was a query (involved a question mark), receive the instrument response.

     if (command.IndexOf("?") >= 0)

     {

      return Response(client);

     }

     return "";

   }

   static string Response(Socket client)

   {

     // Buffer to store the response bytes.

     // For simplicity of this example, we allocate just for a 256-byte maximum

     // response size.

     Byte[] data = new Byte[256];

     // Read the batch of response bytes.

     Int32 byteCount = client.Receive(data);

     // String to store the response ASCII representation.

     string responseData = System.Text.Encoding.ASCII.GetString(data, 0, byteCount);

     Console.WriteLine("Received: {0}", responseData);

     return responseData;

   }

   static void BeginListeningForAsyncReply(Socket client)

   {

     if (m_pCallbackFunc == null)

     {

      m_pCallbackFunc = new AsyncCallback(OnMessageReceived);

     }

     SocketPacket socPkt = new SocketPacket();

     socPkt.thisSocket = client;

     // Start asynchronously listening for a response from this client

     IAsyncResult result = client.BeginReceive (socPkt.data,

      0, socPkt.data.Length,

      SocketFlags.None,

      m_pCallbackFunc,

      socPkt);

   }

   class SocketPacket

   {

     public Socket thisSocket;

     // For simplicity of this example, we allocate just for a 256-byte maximum

     // response size.

     public Byte[] data = new Byte[256];

   }

   static void OnMessageReceived(IAsyncResult asyn)

   {

     SocketPacket socPkt = (SocketPacket)asyn.AsyncState ;

     Int32 byteCount = socPkt.thisSocket.EndReceive(asyn);

     m_AsyncReply = System.Text.Encoding.ASCII.GetString(socPkt.data, 0, byteCount);

     Console.WriteLine("Received: {0}", m_AsyncReply);

   }  

  }

}