Hi Melzi,
I'm not sure if you are still having issues (your post was on 7/5/06), but the NI-Switch 1.6 driver is the latest you can use with LabVIEW 6i. I strongly recommend upgrading to a later version of LabVIEW so that you can use the latest and greatest versions of NI-Switch, providing you with an interactive Soft Front Panel and simpler-to-implement multi-module scanning features.
If you cannot upgrade, then I suggest installing NI-Switch 1.6. This version can be found on our web site at the following location:
NI-Switch Version 1.6 for Windows 95/98/NT/2000/ME
https://www.ni.com/en/support/downloads/drivers/download.ni-switch.html#324280
Inside the attached readmeSwitch.htm file, you'll see how you can access the PXI-2501 in LabVIEW 6i. Let me know if you have further questions or if this does not resolve your issue!
Chad Erickson
Switch Product Support Engineer
NI - USA
