When the RTS Toggle Flow Control setting is selected, the Flow Control is managed by the operating system of the PC on which ClearSCADA is running.
With RTS Toggle Flow Control, messages from ClearSCADA are passed to the operating system. The operating then raises an RTS line by asserting a Request to Send (RTS) signal to the 'receiving' communications equipment. The operating system will then send the data.
When the transmission buffer is empty, it turns off the RTS signal.