When a System Generator token is in a subsystem, the DDS v5_0 block reports the following error:
"Unable to target device family "". DDS v5 can only be used with the following device families: Spartan2 Spartan2E Spartan3 Spartan3E Virtex VirtexE Virtex2 Virtex2P Virtex4"
I am already targeting one of these supported devices.
This problem is caused by a known issue that does not allow the DDS block to see the System Generator token when it is not at the top level of the model. To work around this issue, place the System Generator token at the top level.
This issue is fixed in System Generator 9.1.