Which distro is the best?

[gtg811q]

I'm developing a real-time system using Xenomai. For our project we will be using some NI PXI cards. Currently I'm playing around with Xenomai in Ubuntu. Unfortunately NI doesn't support Ubuntu which has made talking to my PXI cards a hassle. At this stage I can easily switch OS's but I'd like to chose one that will be easier to strip-down later when I start really building our system. As such I'd like to get the community's opinion on which of the NI supported distros is easiest to work with using NI DAQmx and Xenomai or something like it.

By the way Xenomai, which I'm very new to, is a real-time extension to the Linux kernel. I've seen it mentioned on the forums and some have gotten Xenomai, Ubuntu and NI DAQmx to play nice.

-Phillip

[titpoul]

not so nice in my opinion, with the obstacle course to get DAQmxBase work on Ubuntu, and you won't have realtime management of your NI card. However, your PXI card is likely to be supported by Comedi drivers, which have a realtime API for RTAI (it's in development for Xenomai, contact Alexis Berlemont for more info). In addition, RTAI comes with RTAI-Lab which contains Comedi I/O blocks for Simulink and Scicos. In combination with Scicos, you can obtain automatic real-time code generation from block diagram. I used Ubuntu+RTAI+Comedi+Scicos for closed-loop control at 5 kHz, and QRtaiLab as a virtual oscilloscope and monitoring application.

[metux]

I'm developing a real-time system using Xenomai. For our project we will be using some NI PXI cards. 

Be careful to just pick those cards, which there are already free IIO/Comedi drivers for.

If you wanna use them in Xenomai RT domain, you'll either have to adapt IIO/Comedi for that (eg. locking, not calling any Linux domain services directly) or write completely own drivers. Otherwise you won't get the Xenomai low latency features with these cards.

Unfortunately NI doesn't support Ubuntu which has made talking to my PXI cards a hassle.

NI only "supports" a few distro's in a few specific versions and a few specific kernel versions and configurations. Of course, it doesn't include any RT environment. 

As such I'd like to get the community's opinion on which of the NI supported distros is easiest to work with using NI DAQmx and Xenomai or something like it.

None.

By the way Xenomai, which I'm very new to, is a real-time extension to the Linux kernel. I've seen it mentioned on the forums and some have gotten Xenomai, Ubuntu and NI DAQmx to play nice.

Unlikely. At least, DAQmx won't run in RT-context - just as a usual low priority Linux process.