I'm pleased to announce that, thanks to the remote support of Jeff, I succeeded in using an HxC SD floppy emulator in my FM-TOWNS Marty 2.
Here are video (sorry for black&white screen but my TV doesn't accept NTSC signal) I made during a reading and fomatting of a disk image :
Actually the HC was already 100% compatible with the FM-TOWNS Marty, techncally speaking the problem was that the READ DATA output signal from HxC was slightly off what the Marty expected.Jeff suggested me to install a 220 Ohm pull-up resistor between the READ DATA line and 5V, this did the job so now we can enjoy his wonderful device in out Marty console.
Attached is the connection diagram between the HxC (or real FDD like a modified Samsung SFD-321B) and Marty, remember only to put a resistor (220 Ohm but other values up to 1K are fine) between pin 30 (READ DATA) on the HxC header and +5V.Later revision (Rev F and slim) of HxC have footprints to accomodate pull-up resistors.Mine was a Rev.C so I put the resistor on solderside of HxC but you can install it also on your custom adatper.About that I remember that Marty use a 26pin FFC connector with 1.25mm of pitch so you have to build an adapter to 34 pin IDC.I'm working on designing an adapter.
As for HxC you can set the interface on "AUTO" or "SHUGART" and all other settings "FROM HFE"
Many thanks again to Jeff for his support (and patience too...)