Null Modem Cable for Datafire Sync2000


Has anyone managed to create a working Null Modem cable between 2 ports of a Sync2000? I made one that shows all my unbalanced modem signals (RTS, CTS, DSR etc.) as asserted and set clock to internal (in software) on one side but can’t get any data through. Are there any DIP swithes that change port from DTE to DCE that need setting in order to force a clock from the adapter?