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Mixed network topology with cRIO and cDAQ: how to accomplish it?


Hi NI community, 


I am in the process of putting a large control and data acquisition together and in the process I see much of the system I would have picked have gone obsolete. This forces me to change the topology I had in mind. I hope someone can help me figure out if I am making a mistake on my assumptions.


My challenges is that I cannot test these topolofy as all the units in the system are to be purchased once the system is designed.


In a previous question I discussed my system idea:


1. cRIO 9049 (host, RT/FPGA deterministic control)

2. cRIO expansion chassis (RT/FPGA expansion deterministic control) -> NI 9145 (as per NI recomendation)

3. cDAQ 9189 (Data acquisition 8 slots)


NI recommends to expand cRIO with EtherCat for deterministic control or MXI express. However, if you want to control a cDAQ from a cRIO you are limited to cRIO 904x - 905x and these chassis do not support MXI connection. As a result, I am left (I think) with EtherCat to achieve the cRIO expansion.


If my assumption is correct, I cannot see how I can connect the cDAQ while maintaining the DAQmx capabilities given that the Ethercat cRIO expansion does not have this capability and would prevent the cDAQ chassis from working, if connected in a daisy chain kind of network.

NI daisy chainned.jpg

where the host is a cRIO 9049, the 1st node is a NI-9145 and the last node is a cDAQ 9189. However I have not find any information related to cDAQ and EtherCat.


My other option is to use a start topology (figure below) but then I doubt the connection would follow Ethercat protocol and this my "deterministic control" will not be accomplished.

NI start topology.jpg


My request to NI here is to explain how the new cRIO 904x - 905x can be expanded and connected in a way that deterministic control and DAQmx capabilities are maintained?

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Message 1 of 5

Hi misieaz,


The detailed information please refer to the following link: .

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Message 2 of 5

Thanks zhengchen but this article does not explain how to SIMULTANEOUSLY and in a DETERMINISTIC fashion create a network of cRIO 904x + cRIO expansion chassis + cDAQ chassis. It only explain how to do one or the other!


I need to do it simultaneously. At the end I am working with independent cRIO + Expansion, and cDAQ chassis which sync via a timing trigger across the PFI port. However in these arrangement cRIO and cDAQ are not passing data among each other which is a bummer for my system.


Hope my comments are clear


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Message 3 of 5

I'm in the process of creating several multi-cRIO deterministic systems, some w/ channel expansion on a cDAQ. The larger system will be 6x cRIO-9045's, 4 of them will have cDAQ expansions. To solve the problem you are tackling, I'm using more than one full cRIO controllers connected via TSN for deterministic messaging. I'm not using an expansion chassis. Perhaps this could work for you as well. 

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Message 4 of 5

Thanks for your answer wrkcrw00


In my case we need the expansion chassis. You could use controllers but that does not make it very affordable. 

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Message 5 of 5