Can't find a 15 Pin Sub-D to Mini-USB anywhere
15 pin to usb adapter help
DIY cable/ ALDL to 15 pin serial? - Third Generation F-Body Message Boards
15-pin serial adapter for USB not possible? Help! - Factual Questions - Straight Dope Message Board
Hard to tell without a pic, but I'd guess its a 'DB Connector' or 'Game Port' connector.
DB-15 (DA-15 and DE-15)
Two DB-15 connectors are widely used. The larger, two-row female DA-15 is the game port on a PC, and the smaller, three-row, female high-density DE-15 is the VGA port.
The Game Port was used for joysticks, midi devices and other peripherals.

source
A couple of our earlier generation terminal concentrator units ran on an RS-422 loop that used DB-15 connectors and cabling.
Hi,
I am trying to connect a frequency converter to my computer to make it work with a software. Unfortunately the connector I need is from a company that has not replied to any of my emails. Would anyone know if anyone sells this specific adapter?
It is a 15 pin adapter to mini-USB
***Update
Sorry, it didn't seem to attach the picture I wanted to show, here is the link to what the adapter looks like, https://imgur.com/DRpi7nU
This is the website of the manufacture.
https://bmr-gmbh.com/zubehoer.htm
I have the diagram of the pins https://i.imgur.com/LPq3psK.png
I have an old Cyborg joystick with a 15 pin cable. I don't have a port for this on my pc. Is it worth getting a usb adapter? Any recommendations, experience or ideas are greatly appreciated