gpsdso adding an rs232 port

[ME]

I have just ordered this gpsdso from aliexpress, I see on some videos that some have an rs-232 port on the rear, the one i ordere doesent have one, Is it possible to add one and has anyone tried one of these  things, I want it to cal my freq counters.
https://www.aliexpress.com/item/1005007363524269.html?spm=a2g0o.order_detail.order_detail_item.3.2aa5f19c9PosZO