Using cRIO to publish DAQ from cDAQ?

[ckc8302]

All,

I have been working on incorporating cRIO (9073) DAQ into (2) existing and adjacent environmental test chambers to improve resolution of DAQ and controllability. My NI hardware plan included installing one cRIO 9073 in an enclosure behind each chamber with wiring for TC/4-20mA/RTD DAQ run through conduit into the chamber to the EUT. Both of these cRIOs will be running RT code publishing their data to a local network. In the control room for the chambers, there are two PCs which will BOTH be polling the network for all data from BOTH cRIOs. In this way, operators can choose either PC for either chamber at any time.

Now, for my issue. It has been requested that we purchase either cDAQ-9171 (USB) or a cDAQ-9181 (Ethernet) and install one in each chamber. These single module DAQs will each contain a 16 TC card (NI 9214). The reason for this is to save money (we will save a bunch of TC wire and connectors by installing this single modue DAQ very close to the EUT). However, what I need to know is whether or not these products can publish the temperature data to the network without direct connection to a PC. My research leads me to believe that they can not do this alone, but the cDAQ-9171 (USB) Specifications state that the OS/Target can be either Windows or Real-Time. Does this mean that I can connect the cDAQ to the cRIO and include some RT code on the cRIO to publish the data from the cDAQ to the network at a constant rate?

Ideally, we had wanted to purchase the cDAQ-9181 (ethernet) and simply connect it to the local network as a standalone device, but I don't believe that it is capable of running RT code to publish it's own data to the network at a constant rate without connection to a PC; is this true or am I misunderstanding it's capability?

I need to make the decision whether to attempt to install a single module cDAQ to cut down on wire lengths and connectors, or whether I'm better off just running everything back to the cRIO.

Thanks!!!

[Tom_W_[DE] · Accepted solution]

Hi ckc8302-

Your assumption is correct- none of the single- or multi-slot USB, ethernet, or wireless CompactDAQ chassis are capable of running code in a stand-alone fashion like you are used to with your cRIO with LabVIEW RT and/or LabVIEW FPGA.  You can use a stand-alone cDAQ for this purpose (like the cDAQ-9139), but that almost certainly defeats the cost-saving goal you're trying to satisfy for this case.

You are also correct in saying that USB cDAQ (9171, 9174, 9178) are supported with LabVIEW RT targets in general, but the caveat is that they are only supported with x86/x64 targets like cDAQ-9138/9139, cRIO-9081/9082, and PXI systems.  The value cRIO controllers use a different processor and O/S architecture to implement LabVIEW RT support, and those targets are unfortunately not supported by NI-DAQmx and CompactDAQ.

One option you could consider would be to purchase an inexpensive computer and either run a version of Windows on it or make it into an RT desktop for use with LabVIEW RT.  You could then use that to host your proposed USB cDAQ solution, and you could run LabVIEW code on that desktop machine to publish data over the network for consumption by your existing cRIO systems.  The only other alternative I could think of at this time would be to continue cabling your TC sensors out to your cRIO systems like you mentioned.

Hopefully this helps-

[Craig_]

If you go the route of RT Desktop connnected to cDAQ as Tom noted please note that LabVIEW Real-Time only supports the cDAQ-917x USB series of Compact DAQ!

This is mentioned in the DAQmx 9.8 readme here: http://download.ni.com/support/softlib//multifunction_daq/nidaqmx/9.8/readme.html in the "CompactDAQ Chassis"

More information about how to make a Real-Time desktop can be found here: 

Converting a Desktop PC to a LabVIEW Real-Time Target: http://www.ni.com/white-paper/2733/en/

[ckc8302]

Tom_W_[DE],

Thank you so much and Kudos! Your answer is exactly what I was looking for. I really appreciate your throrough reply. NI provides such a wealth of information that sometimes specific details can be a little hard to find. I'm just going to run my TC wiring back to the cRIO for now. This isn't a big deal. Again, thanks for clearing that all up.

[ckc8302]

Craig_

Thank you as well for the additional information. Very helpful indeed.

[Kemens]

Posting to an old thread, but since the info here is good, I wanted to add updates to it.  

TSN cDAQs can be controlled directly by TSN cRIOs (9035 sync, 9039 sync) as well as IC-317x (3171/2/3).

More details on Can I Control a cDAQ From a cRIO?

[LoveTheFactory]

Link broken at bottom of thread, from "Can I Control a cDAQ From a cRIO?" @Kemens . https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019NYwSAM Is there another ?