Examples using NI-9775 with cDAQ chassis

[vix]

Where I can find some examples on how to use NI-9775 with a cDAQ chassis (not cRIO).

I can't find them in Example Finder; it can be that I must search them using a different key..

[aeastet]

Looks like this module is only for c RIO.

The NI 9775, a 4-channel digitizer, can measure transient phenomenon like faults in electricaltransmission lines from lightning strikes or structural failure events at 20 MS/s/ch. Themodule's store and forward architecture allows up to 128 Mbits of measurement data to be sentback to the controller and analyzed. The module has a built-in analog reference trigger, or youcan use CompactRIO and LabVIEW FPGA to develop an advanced trigger based on low-speed streaming data for added flexibility.

[vix]

I'm not sure about it, for a couple of reasons:

• here I can see NI-9775 listed as compatible with comactDAQ
• the same in the manual

Where did you find that info?

Thanks

[EricWilliamsEPT]

Did you ever get an answer to either of your questions (either the original or the follow-up)? We are looking to use the NI-9775 to repeatedly capture high speed data and save that data to a file for post-processing. I'm hoping there is an example of someone doing this out there. Did you ever get your project started?

[vix]

Hi @EricWilliamsEPT,

I've never received any answer

[lroshak]

There are examples installed with the CompactRIO and drivers.  Does not install in the 64-bit version of LabVIEW.  But if you open the 32-bit version and look for 9775 you should find:

 The path is Toolkits and Modules->FPGA->CompactRio->Analog Input.

Just registered that you have a cDAQ chassis.  Let me check if I can find anything.

[lroshak]

Same idea as the cRIO, but in the DAQmx section of the help:  Browse Task.

Hardware Input and output -> DAQmx -> Analog Input....

Analog Input - Filtering.vi calls out NI 9775 support.

I did not have a module but created a simulated cDAQ-9185 added the NI 9775 and ran it in continuous.  Seems to match the documentation on streaming 4MS/s max rate in continuous mode. 

 In finite mode all channels can be captured at 20MS/s/ch but the buffer is shared so you are limited to a total of 8.38861MS/s for 1 ch and 8.38861 / 4 MS/s .

Attached my modifications to the standard example.

[engraqeel]

I am planning to purchase NI-9775 with cDAQ 9171, and I want to use only one channel for continuous data acquisition mode. Will I get the 20 MS/s rate for single channel? If yes what are the other limitations of NI-9775 with cDAQ 9171.

[GerdW]

Hi engraqeel,

---

@engraqeel wrote:

I am planning to purchase NI-9775 with cDAQ 9171, and I want to use only one channel for continuous data acquisition mode. Will I get the 20 MS/s rate for single channel? If yes what are the other limitations of NI-9775 with cDAQ 9171.

---

• The cDAQ9171 is offered with a USB2 interface, this means the communication is limited to 480Mbit/s (raw!). This typically results in up to 40MB/s transfer speeds (due to data encoding and transfer protocols)…
• You want to read 20MS/s: with 16bit data this will need 40MB/s, with 32bit data you request for 80MB/s.

For me this reads like a typical conflict between requirements and hardware capabilities…

Generic suggestion:

When you want to handle high-speed data acquisitions you should use suitable hardware!

Asking for (old) USB2 devices is asking for trouble: look for other better options…

[mcduff]

---

@engraqeel wrote:

I am planning to purchase NI-9775 with cDAQ 9171, and I want to use only one channel for continuous data acquisition mode. Will I get the 20 MS/s rate for single channel? If yes what are the other limitations of NI-9775 with cDAQ 9171.

---

If you look at the previous message and the documentation, you will see that 4MSa/s for 1 Channel is possible in Continuous Acquisition mode. The higher sample rate is only available for finite acquisitions of a single channel.