'm a bit lost, with the photo. Are you talking about the 'D' connector, labeled 'IOIOI', or the small flat socket in the centre??
The Centre one looks like the new USB Type-C which relies on numerous specific external devices for utilization.
The other looks like RS-232 (having the IOIOI label?), which is an old original Standard for Serial Communications.
Many old devices and security equipment etc was able to be plugged in, and with elementary software set up to 'talk' using
parameters such as Parity, Baud, Data etc, you could analyze/change information in numerous devices. There are numerous
cheap interconnecting cables that can be used, for a multitude of such field devices! (Literally a few dollars).
It's surprising that a modern device would include that? When most people need/want that, (old RS-232), one either obtains
an equally cheap USB adapter/cable, or uses an old cheap $30 2nd hand laptop that will do the job perfectly.
However, if you are talking about the Centre socket, (USB Type-C), then I recently purchased an adaptor, like in the following
image, to (one of numerous uses) adapt it to 4 USB 3 sockets...