Neither I nor the supplier had a part number for them. We received the Stereo Mini-USB adaptors from our supplier.

In fact, I have another post on here recently about issues I have encountered. I just finished a job with these and I am happy to share the info. I just used this feature with a slew of MU6000 TVs. I'll let you know if we figure anything out, and would greatly appreciate if you'd do the same. Neither of the devices show anything about being some sort of COM port, though. There are a few things that show in Device Manager, but we haven't been able to find drivers for those devices. We were able to get a PC to sort of recognize the TV when connecting directly to the USB port thinking that maybe Samsung had built the serial adapter directly into the TV. We have a ton of TRENDnet adapters we purchased for the PC side. Those adapters usually require a driver though, and we haven't been able to find out which ones might be compatible. From my understanding, they do run some flavor of Linux so it's entirely possible that would work.

We haven't tried putting a USB RS232 adapter on the TV yet. I'm also glad to see you mention a USB-RS232 adapter.there is an option in the Service Menu that says 'USB Serial'. Glad to know I'm not the only one who has run into this issue.