This has been covered in the past. Due to liability issues at some point in the past the ability to control the AT1000PRO2 and 600 was removed from the firmware. This was instituted due to some operators using it to remotely control the tuner when using QRO power levels. I'm sure this was a liability that LDG did not want to be exposed to. I'm sure that is also the reason they discontinued the external meter since it uses the same TTL port and protocols to communicate. Since the logic is TTL level if you have an older firmware you could easily build a cable with a S-video cable and a usb to ttl adapter.? YMMV
de N5KBP
