Are you certain you need all wires connected? Can you get by with 2 wires sending data? (Ground & Tx)
Or 3 wires forming a null modem? (Ground, Tx, Rx) It doesn't give you the handshaking, but it's easy.
If you need functions on all wires, then you must identify the purpose of all pins coming from your two devices. You must match them one-to-one. It may not be an easy taske. The manufacturers do not always give sufficient information to make it easy.
Here are some pinouts found via internet search. I'll bet they're all different.