If you're referring to synchronizing your FPGA with the analog input operations of the PXI-6025E, there are several examples that will allow you to do so. In LabVIEW, they are in the the LabVIEW >> Examples >> Daq >> anlogin directory and are the ones that say "ExtScanClk" appended to the end. You can externally apply a scan clock, and the VI Documentation will describe this. With NI-DAQ function calls, you will find examples in the NI-DAQ >> Examples directory.
If you are trying to synchronize the digital lines of that 8255 chip on the PXI-6025E, you will use a method of handshaking, and wire to the appropriate handshaking lines. These examples are in the LabVIEW >> Examples >> Daq >> Digital >> 8255 directory or in the NI-DAQ >> Examples directory. For the lat
ter case, make sure you look at the examples with "8255" appended.
You will also find the 6023E/6024E/6025E User Manual helpful, which you can find on the website. It will show you the pinouts for connecting your signals.
Regards,
Geneva L.
Applications Engineer
National Instruments
http://www.ni.com/support