I've just ordered couple of these cables. To make them works with my JTAG connector, I built a little 10 inches thong adapter, one end connects to the existing Xilinx 2.5 mm ribbon connector, the other end fits to my JTAG connector. The total legnth of the Xilinx ribbon and the thong is about 16 inches.
Now comes the mistery, whenever I try to program the devices (proms) iMPACT 9.1i reported bla.. bla.. bla.. the device ID doesn't match bsld, It's really a headache, trying upgrade drivers, service packs, bsld,...nothing helped at all, I also ran all available speeds from slowest to max, result were the same
As my last trial I made the thong a half legnth as before, total legnth now about 11 inches, as you guess, it worked
Is there any doc/manual that specify the max legnth for this cable?