STM32f4 + CubeMx + LwIP

Hello,

       I want to use LwIP in server mode. After a client has connected, I want to send data periodically to the client. 

       My device, 'STM32F4' is the server and the PC is the client.

       By using the 'tcp_echoserver' example, I can only send data from the server side to the client side, When I get data from client. 

      Can somebody recommend a solution or share a code ?

Best Regards