Qtusb for Bulk Transfer

[HKH1988]

Dear Friends
i have project that i should use serial port of android device
as I search it in forum and internet I find out I should root android if I want to use serial port
but I can not root my android tablet, I try most of known way for rooting device but I cant root it (if you know some special way to root it please let me ) so I try to use qtusb but before to test it on android I try to test in windows app, I can not send bulk transfer to pl2303 when I try to send it to pl2303 I faced to this message I try to use bulktransfer on my mouse razer deathadder I don't see this error so I know the code is working but I can not use bulk transfer on pl2303 ,thank you fro your consideration
I use example code in qt USB in link below:
https://github.com/fpoussin/QtUsb
if I can not use serial port I think I should go for Bluetooth device