On a Windows machine, initializing a JTAG chain in iMPACT 6.1i produces the following error:
"Cannot find instruction ISPENABLE."
Generating an SVF file also produces the same error; the instruction reported may be different.
This problem is caused by a very long PATH environment variable on a Windows machine in which the Xilinx path is at or near the end. If the PATH value overflows the fixed amount specified by Windows, the overflow data is ignored.
To resolve the issue, move the Xilinx path information to the beginning of the PATH environment variable.