It does not even look like the pins are present in some of the places they should be. I am guessing the mfr. put their wires wherever and it is up to you to adapt them back.
If I was going to be working on this equipment a lot, I would try and make an adapter from that panel mount connector to something standard. In the meantime, I would figure out what wires are on what pins by schematic and physical/voltmeter verification if possible, and temporarily connect it with alligator clips or something.
Here is something that might work, buy this cable, shave off the center keyway, and cut/splice/rearrange wires as needed. I don't know if your existing data link connector has the fat or skinny housings on C and J, though.
https://www.ebay.com/itm/353548268546
If that Y-adapter does not have all wires where expected, I bought one of these and made my own adapter for another manufacturer's equipment:
https://www.ebay.com/itm/252959288343
If you really want to roll your own:
https://www.ebay.com/itm/333979707693
My laptop bag is getting really full of cables I have made.