When reading back Configuration memory it is recommended to shut down the device.
If you must read back the Configuration memory while the device is operational, LUTRAM and SRL16's must be masked out.
The BitGen option below can be used to set the GLUTMASK_b mask bit correctly.
However it should only be used in the following conditions:
1) The design does NOT contain the typical readback mechanisms such as the Frame _ECC primitive or enabling of the POST_CRC feature.
2) The device is being read back while operational.
Note: This must be manually entered into the Other BitGen Command Line Options field as shown below:
This is applicable to ISE tool versions 12.1 through 14.7.