布线失败,ERROR:pack:2162 - The I/O component DDR_DM[2] has an I/O standard value SSTL15
that can not be applied to an IOBUF symbol. Please correct the IOSTANDARD
property value or the symbol it is applied to.我在ucf 文件里面定义了 NET "DDR_DM*" IOSTANDARD=SSTL15;
请问这是怎么个情况?多谢指点