USB-RS485 attempting to figgure out if unit is bad or device has issues

Im trying to determain if the rs485 device is bad or good.

on rs232 you could loop the rx and tx and it would give you the same input as you typed telling you the device is good. however on this device if i do the same thing it is giving me different things back then what im typeing… how do i know of this device is good or bad?
thanks.

example i type “y” i get a “C” back.

In order to perform a loopback test on an RS-485 device, you will need to connect R- to T- and R+ to T+. Than you should get back the same message you send.