I have encountered a problem where MAP will fail with the following error if a OBUFTDS symbol is configured with a constant input:
"INTERNAL_ERROR:Pack:pkibadbmend.c:184:184.108.40.206 - Found an incomplete connection
on comp block i_cabo/GND/N. The signal GLOBAL_LOGIC0 was found on the comp
block pin G1, but no child signal exists.
FATAL_ERROR:Pack:pkivrlogicmend.c:304:220.127.116.11 - Comp i_cabo/GND/N: Missing LUT
input signal on LUT Bel. Process will terminate. To resolve this error,
please consult the Answers Database and other online resources at
http://support.xilinx.com. If you need further assistance, please open a
Webcase by clicking on the "WebCase" link at http://support.xilinx.com"
This problem has also been encountered with constants driving OBUFDS symbols, resulting in the following error:
"FATAL_ERROR:Ncd:basncsignal.c:283:18.104.22.168 - Could not find a bel for a signal
on pin G1 of comp GND/N. Its current programmed state is : YUSED:0
G:#LUT:D=1 Process will terminate. To resolve this error, please consult
the Answers Database and other online resources at http://support.xilinx.com.
If you need further assistance, please open a Webcase by clicking on the
"WebCase" link at http://support.xilinx.com"
Both failure modes are related to the incorrect configuration of a LUT inserted to source the constant.
This problem has been fixed in the latest 7.1i Service Pack, available at:
The first service pack containing the fix is 7.1i Service Pack 3.
A tactical patch is also available for download for all 7.1i versions prior to Service Pack 3 at:
This file is compatible with all platforms and can be installed by unzipping it in the "XILINX" directory while maintaining directory structure.
If you are encountering this problem in version 6.3i, you can work around it by avoiding constant inputs on OBUFDS and OBUFTDS symbols. If this is not possible, it is necessary to configure the constant so that it is isolated from the output buffers. In one case, this was done successfully with an SRL16e configured with CE='0' and INIT="0000".