If you select the 'Config | Connection Config' from menu bar, you can see the dialog box like <Figure 1>.
<Figure 1> Example for Connection Config setting dialog box. (In case of failing to connect)
If the part of 
in <Figure 1> is checked and sets the Retry Time (between 1 and 5000 min), when
OPC Server fail to connect, it is retry to connect according to Retry Time which
you set.
If OPC Server is currently connected or it is connected by reconnection, it doesn't retry to connect anymore.
Relate items)