NI-DAQ (NIDAQ32.LIB) is not supported under RTX. You will have to develop your own driver in order to interface with a data acquisition device under RTX.
The Measurement Hardware Driver Development Kit (DDK)provides development tools and a register-level programming interface for NI data acquisition hardware. I've included a link below. I hope this helps.
Measurement Hardware Driver Development Kit (DDK)
http://sine.ni.com/apps/we/nioc.vp?cid=11737〈=US
Regards,
Todd D.