Hi,
I'm going to need a little more information to help you. Have you installed the DAQmx driver? This will recognize the Switch device. The driver can be downloaded here:
If you've done that, then are you using a controller or a MXI interface?
If using MXI, make sure your chassis is powered on before the PC. You should get a Windows "Found New Hardware" Wizard when you startup.
Do you have other devices in your PXI chassis? Are they showing up in MAX? If so, try moving the 2503 to another slot and rebooting. Additionally you can check Windows Device Manager and see if an unrecognized device is there (there should be an exclamation point by it) then you can point that device to your NI-Switch driver to use it. The NI-Switch driver can be found here:
Hope this helps, let me know if you still have questions!
B Spears