I am confused and stuck when trying to connect to a channel using JSch or Socket?

Question

So I am trying to connect to a device that is going to acquire analogue data(Red Pitaya). It has set scpi commands that control the device. I can control these through labview and using putty.

I am trying to write and android application that can access the devices scpi server and send commands to it for the device to complete.

The device is programmed in a way in that you first have to connect to the server using a SSH connection which i have no problem doing using JSch, from there you can send a command to start the scpi server and open a connection.

Now this is the bit i am struggling with and i dont understand why, when the SCPI server has started it is accessed through the Ip of the device and a raw port of 5000, but i cannot seem to write a piece of code that connects to this and performs a SCPI command. I am not to sure whether it is the connection or the way i have sent the data.

This is the code

public class rp_command extends AsyncTask<Void,Void, Void> {
String ipAddress;
int port;
String response = "";
TextView textResponse;


rp_command(String address, int rp_port, TextView textResponse){
    ipAddress = address;
    port = rp_port;
    this.textResponse = textResponse;

}
@Override
protected Void doInBackground(Void...arg0){
    Socket socket = null;

    try{
        socket = new Socket(ipAddress, port);   
        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        out.writeByte(1);
        out.writeUTF("DIG:PIN LED2,1");
        out.flush();


    } catch (UnknownHostException e){
        e.printStackTrace();
        response = "UnknownHostException:" + e.toString();
    } catch (IOException e){
        e.printStackTrace();
        response = "IOException:" + e.toString();
    } finally {
        if (socket != null) {
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }return null;


}
@Override
protected void onPostExecute(Void result){
    textResponse.setText(response);
    super.onPostExecute(result);
}

}

If anyone has any advice it would be appreciated thanks

Answer 1

Got it working here i believe the issue was due to not ending a command with \r\n being at the end of the string here is the working test code if anyone is interested. This is for sending a string not receiving.

public class MainActivity extends AppCompatActivity {
Socket s = new Socket();
PrintWriter s_out;
BufferedReader s_in;
String out = null;



public void sendCommand (String command){
    try {
        s_out = new PrintWriter(s.getOutputStream(), true);
        s_out.println(command);
    }catch (IOException e){
        System.out.println(e);
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Button LED_ON, LED_OFF;

    LED_ON = (Button)findViewById(R.id.button);
    LED_OFF = (Button)findViewById(R.id.button2);

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy);

    try{
        s.connect(new InetSocketAddress("192.168.0.104", 5000));
    }catch (IOException e){
        System.out.println(e);
    }

    LED_ON.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            sendCommand("DIG:PIN LED2,1\r\n");

        }
    });
    LED_OFF.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            sendCommand("DIG:PIN LED2,0\r\n");
        }
    });
}

}

When using buttons to initiate a command i noticed that if you write the send command code in there instead of a separate function the app would time out and crash.