Can I connect a RS422 slave to the Barionet50?

For the Barionet50 are RS232 and RS485 specified on the datasheet. That´s so far also correct.

But you should know RS485 2-wire and RS422 2 wire are almost the same, but ....

When you have only one serial master (e.g. the Barionet50) and one RS422 device then it is no problem to connect that to the Barionet50´s RS485 interface. If you have multiple RS422 slaves then you can also connect these to the Barionet50 but you have to make sure that each connected directly to the serial main bus and not "daisy chained" behind another RS422 slave.

RS485 (and RS422) 4-wire is only supported on the Barionet100, but not on the Barionet50.