In hopes of saving someone from some head-scratching: if you happen to have a Siglent oscilloscope, and a Siglent signal generator, and you can’t get the two to communicate over USB while using the Bode II measurement feature of the oscilloscope, check the “GPIB” setting on the signal generator. It needs to be set to 1. For reasons unknown, it was set to 18 on my SDG 1025. Yes, it doesn’t make any sense because GPIB is a different interface standard than USB, and this particular signal generator doesn’t even have GPIB, but before I figured this out my SDS 1104X-E ‘scope would always report that it couldn’t find the signal generator. I looked for any setting at all in both instruments which seemed to be relevant, and finally set the GPIB number on the signal generator to 1 simply because 18 seemed like an unlikely value. After that everything worked.