[weblacky]

I'm seeking information or recommendations about compatible adapters for listening to COM1 on the IRIS Indigo through USB, as I'm planning to use it for checking any messages that may appear during the initial power-on diagnostics, etc. I've found limited online resources about this and would appreciate any specific knowledge or insights anyone might have.

It's not proprietary, it's RS-422.  So buy a USB to RS422 adapter (page 181-182): http://www.sgistuff.net/hardware/systems...indigo.pdf

Then cable it to a Mindin-8 with parts from Mouser or digikey.

The Iris Indigo keyboard/mouse port IS proprietary, not the rest.

I don't know much about the difference but I think a "Computer to Device cable" : https://ipc2u.com/articles/knowledge-bas...nd-rs-485/

Looks like you need to make a DB9 to MiniDin-8 converter cable.  Use Pinout signal info in indigo manual to creeate a signal match.

Thanks.