Hello laidesheng,
Detailed knowledge of the MANTIS and MITE ASICs is not required in order to use NI's MXI-2 products, as you can use the NI-VXI driver for your programming needs.
If you are looking for resources to develop your own MXI and VXI based products, then some good starting points are:
National Instruments KnowledgeBase:
What is the PCI-MXI-2 Driver Developer Kit?Also, you can find more information on the VXI specifications at the VXI Consortium webpage (http://www.vxi.org/)
Regards,
Joshua Hernstrom
PXI/VXI Support
National Instruments