Genral Description: When I try to bring out a node to a port for debugging, the "add probe" window does not list the Vref pins on a Virtex Device.
Solution
The 2.1i FPGA Editor is unable to access the I/O Standard information of the different Virtex banks. Therefore, by default, it assumes that the Vref pins are being used for Select I/O, and does not list them.
To use a Vref port for an internal strobe, the connection must be made manually.