+ AA6YQ comments below
The Green Heron RT21 that I have is an older serial model and its usb port also disappears when you power it off. But I have a different problem. Art's issue is that he forgot to turn it on before starting up DXV. So the "Enable on Startup" fixes his issue of re-finding the now powered on port when he starts DXV. The issue that I have is that I'm leaving DXV running continuously. The issue is when you turn the controller off and the port goes away, DXV doesn't re-establish communication with the controller after you turn on.
With DXV left running, when I return to the shack and turn the controller on, I have to go into config in DXV, uncheck (regardless of the Enable on Startup), close config, go back into config and check enable, and then hit the bearing button TWICE. Then it will reconnect to the USB port and send the coordinates.
+ Closing DXView's Configuration window has no impact on anything. Unchecking Enable will close the serial port, checking it will re-open the serial port. If clicking the bearing button twice is required, that peculiar to the rotator.
I'm not sure what to ask Dave to do, but I'm thinking the TWICE clicking of the direction button has some input. Maybe if the rotator is set to Green Heron, each rotate request checks the port, if available resets the data (is that what the first click does?), then sends the rotate command.
+ No other Green Heron user is reporting the need for that.
I haven't checked the serial port on the back of the controller, but given the previous thread I'm guessing its related to the fact that the Green Heron's port disappears when its turned off. DXV loses that port somewhere along the way and when you turn it back on, it won't communicate with it until you go through the above procedure to disable and reenable and send the request twice.
+ DXView can't "lose the port". It can direct Windows to close the port (when you uncheck, the Enable box), and it can direct Windows to open the port (when you check the Enable box). Everything else is the responsibility of Windows, the serial port device driver, the serial port, and the rotator controller.