Hi,
Accuracy is a function of the modules in your chassis and the DAQ board that is controlling your chassis. The feedthrough module will not have accuracy specs. The different devices that have accuracy specs are your DAQ Boards and SCXI Modules. You can view the different accuarcy specs w/in the manuals or data sheets of these devices. Then, you can use the online calculator to find out the system accuracy. If the modules are not listed, then you can use this online knowledge base and calculate it yourself:
http://digital.ni.com/public.nsf/websearch/8BA2242D4BCC41B286256D1D00815B90?OpenDocument
I hope this helps...Have a Great Day!
George