Open / Send Multiple Messages Over TCP And Close Connection On Events

I have a simple method in Java through which I send commands to a machine over TCP. The problem is:

Machine can't accept more than two connections in 20 seconds.

I need to send 15-20 commands to the machine in 3 minutes.

This is my current method which is not working as it should, 2 commands get transmited but third command hangs because of the machine.

void sendCommand(String command) throws IOException {
String ipaddress = "192.168.0.2";
Socket commandSocket = null;
BufferedWriter out = null;
BufferedReader in = null;
BufferedWriter outToDetailFile = null;

[Code] .....

Basically what i need is:

1st: I need to open the connection by calling method

public void openConnection(String ipaddress, String port){
//Code to start the connection
}

2nd: I need to be able to send commands to the connection I have already opened (i will send multiple messages in time period of 5-10 minutes):

public void sendCommand(String message){
}

3rd: Close that connection

public void closeConnection(){
}