I am using Avnet's PCIe SP6 board.
I was able to confugure FPGA using iMpact and Xilinx's USB cable.
There's some prob now:
when iMpact is run and asked to do "initialize chain" it detects / displays correct FPGA in GUI.
After that, if "get IDCODE" is done, returns wrong IDCODE and gives INFO:585 msg. Which recommends to check voltages, chain etc.
How at first-place (when impact being run from scratch) impact can detect device? -- when IDCODE being returned is wrong for whatever reason.
[I have checked supply voltages they are corect 3.3, 2.5, 1.2 .... ]