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Using a RTX target in closed loop measurements and control

Hi,
 
I am new with LV RT and LV 8.0. Now I need to set up a closed loop control system using LV 8 RT and a NI USB 6009 as the DAQ device. That is, the USB 6009 is connected directly to the host computer via a USB cable, and the host computer itself also works as the RTX target to control the USB 6009. The host computer is running on XP.
First of all, when I created a real-time target, from the real-time project wizard, I only see the PCI-7041 as a target (or device) when I was asked to browse the local target. How can I set up the host computer as the RTX target? How do I know that the RTX extension is already working? (I can see the RTX is installed since I saw teh path the C:\Program files\National Instruments\LabVIEW8\Target\NI\RT\RTX.)
My second question is that if I use the timed-loop in data acquisitions, how do I set up the loop to run on the RTSS instead of the Windows timer? In other words, how do I specify using the RTSS? I am asking this, because it seems to me that without using the RT module, I am still able to run a timed-loop and set different priorities for different loops under Windows. If this is the case, what is the difference in using the timed-loop between the RTSS and the Windows? Or put it this way, since you already have the timed-loop structure with priority, which can be used to reduce jitters, what is the advantage of using RTSS over using Windows? From this question, a further question would be that, is the timed-loop with highest priority preemptive under Windows?
Thanks in advance for any response to my basic questions about the RT applications.
 
William
 
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Hi William,

 

Unfortunately, USB is not supported in RTX and there is not a solution to use USB DAQ in RTX. You can however use DAQmx Base with RTX and below is a link to a document to help you set this up.

DAQ with RTX

http://digital.ni.com/public.nsf/websearch/482666D94E7551F6862570B3005C3B28?OpenDocument

 

RIO with RTX

http://zone.ni.com/devzone/conceptd.nsf/webmain/8686108353c0bdb586256f9a0069b03c

 

For instructions on Installing RTX please look at the link below and refer to Page 3 on instaling RTX

 

PDF on Installing RTX

http://digital.ni.com/manuals.nsf/websearch/44B8AB0B5C95E54B86257075004ED316

 

LabVIEW Real-Time Module for RTX Targets Troubleshooting

http://zone.ni.com/devzone/conceptd.nsf/webmain/6b7c60b76482639986256e8900736b6a

 

Cont...

 

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cont...

 

Timed loops are not supported on RTX targets as well. Please take a look at the link below for orther features that arent supported either.

 

Software Features not Supported in LabVIEW Real-Time for RTX

http://zone.ni.com/reference/en-XX/help/370622C-01/lvrtconcepts/unsupportedrtx/

 

If the RTX is already running on your computer, an icon which says 'LV for RTX is Running' appears on the system tray at the lower right hand corner of the desktop monitor.  You can also write a simple program and run it to verify that your installation is working fine.

 

Have a great day!

 

Regards,

Prashanth

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Prashanth,

 

Many thanks for your quick response and helpful information.

I may need to digest the information and do some tests on my setup before I ask further questions.

I appreciate your help.

 

Regards,

 

William

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