Rhino UART

I am working on a project where I will use a RHINO board to talk to a barcode slot reader.
The reader has the option to have a USB or serial interface.
They also mentioned TTL interface but I think this is also referring to a serial device.

I saw that Rhino supports serial communications but where on the board do I plug in a serial device.
What pins do I wire to, do I need any additional boards etc.

Thanks
Jim

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