[weblacky]

The USB-to-RS422 adapters provide a DTE port, and the Indigo has a DTE port. So you would need a null-modem type cable.
The standard cable of that type was called an "ImageWriter II cable". Serial printers also have DTE ports.

Can you please track down and post the pinout...I found nothing for NULL modem cabling for a one-to-many RS-422 protocol, that's why I didn't post such a claim myself.  Computer-to-Device cabling on the above site already swaps TX and RX in RS-422 cabling for "computer to device" picture shown..isn't what a cable to dumb terminal would do anyway?  OP asked for serial terminal interface, doesn't the "computer-to-device" cable presented not appear to be that?

Can you please provide a source, I cannot find one single reference to a Null modem cable pinout existing for RS-422, since it's a master-slave (multi-slave capable bus) it doesn't appear to need it.