Those two boxes will work given the corect cord and the corect setup. If you are planing on using the 7C as the transmitting box and the other as the student box, you only need to activate the trainer switch on the 7C. The student box will not even be turned on. That radio is a PPM radio, It would say PCMon the box and receivers if it were PCM. If you hook your 7C up to say a 9C as the student transmitter, the 9Cwould need to be set to PPMmode.

Ifound that a basic TX as a student box will not take advantage of any of the transmitting boxes computer setup, if the TX is a 6eax. I'm sure that there are other TX's that have the same issue. You end up with just raw stick movements from the trainer box, no end points, or expo, or any mixing. The 9C incorporates all the mixes and stuff and any of the old conquest or Attack boxes that were FMmode worked well. I expect the 7C would be close to the 9C in this manner. I would suggest that you check with Bax on the Futaba forum to see if there are any issues between these tow tX's. Botom line is that even if there isn't computer utilization, you can still use them the same as two basic boxes will work.
Now for the simulator cable, You are probably using one of the free simulators, IEFSM, and all those requie the Tx to be in PPMor FM, one in the same, mode. On your 7C, the setting is probably under "Prameters", that is where you set up the mode in both my 9C and 10C transmitters. You also have to setup the USB driver that comes with the software.

Don