Greetings,
The PCI-6224 card has 32 analog input lines. You should be able to read 32 different channels at the same time without too much trouble.
You can find several ready made examples that help out with making analog measurements. If you are using LabVIEW you can go to help, Find Examples.
Let me know if you have any follow-up questions.
Regards,
AnujD.