How to use TCP_TYPE_KEEP_ALIVE or how to hold TCP connection?

I am writing simple program to control device through TCP port. Program was working but connection close automatically after time out. To hold the connection I try to use TCP_TYPE_KEEP_ALIVE flag, but...
How to use TCP_TYPE_KEEP_ALIVE or how to hold TCP connection?

I am writing simple program to control device through TCP port. Program was working but connection close automatically after time out. To hold the connection I try to use TCP_TYPE_KEEP_ALIVE flag, but...