Benchmarking PXIe based Data Acquisition

[falcon98]

Dear Experts,

I wanted to test the available hardware to its limits. I have a PXIe 1065 chassis with Industrial Desktop computer with LV RT connected over MXI. The PXIe chassis has 5 pxi 6259 cards.

I wanted to test the system and made a small program which digitizes 32X5 channels at 31KSPS which is near the maximum acquisition rate supported by 6259 card.

When I am executing the program the cores in Controller are jumping to 99-100% load which I believe is not a good sign. Is there is any solution to achieve this by making some optimizations in the code.

I am attaching my snippet for your reference and comments. I have tried with all the data types. U16, double , waveform and even raw type.

later I aim to add consumer loop for data logging.

Pls give your suggestions.

[mcduff]

1. Since all the cards are identical, you can combine all the channels into 1 task. Thus your five loops go to one loop.
2. Plotting all those points is what is slowing down your pc. See this link for some inspiration.
3. Use the logging features built into DAQmx, you do not need a separate consumer loop.

mcduff

[falcon98]

Thanks for your reply.

When I am trying to combine them to a single tasks , I am getting error stating that one or more device do not support multidevice tasks.

I will remove the graphs and include DAQmx logging and update here.

[falcon98]

Hi,

While using the DAQmx based logging , I am getting strange results. The data is getting plotted properly but in while the data is not logged correctly.

There is loss in the signal shape. Pls see the attached image.. I have executed the inbuilt example for DAQmx based logging.

[mcduff]

You need to post some code, otherwise hard to help.

mcduff

[mcduff]

---

@falcon98 wrote:

Thanks for your reply.

When I am trying to combine them to a single tasks , I am getting error stating that one or more device do not support multidevice tasks.

I will remove the graphs and include DAQmx logging and update here.

---

If the devices are identical, in a PXI chassis, typically they can be combined into a single task. However, if you are using DAQmx with RealTime LabVIEW, that option my not exist as DAQmx is new for LabVIEW RT. I never used it with RT LabVIEW, but with Windows I know it works.

mcduff

[Bob_Schor]

U

---

@mcduff wrote:

---

if you are using DAQmx with RealTime LabVIEW, that option my not exist as DAQmx is new for LabVIEW RT. I never used it with RT LabVIEW, but with Windows I know it works.

---

Um, I forget when DAQmx was released.  In LabVIEW 7.0, we used "Traditional DAQ" on LabVIEW RT running on a PXI (not PXI-e, yet) system.  When I started updating it (LabVIEW 8-something), I used DAQmx (thank goodness I could dump Legacy DAQ!) on my PXI-based LabVIEW RT system -- I think the final update of this particular Project was in LabVIEW 2014.  Not only does DAQmx work well in Windows, it works even better in LabVIEW RT (well, at least as well ...).

Bob Schor

[mcduff]

---

@Bob_Schor wrote:

U

---

@mcduff wrote:

---

if you are using DAQmx with RealTime LabVIEW, that option my not exist as DAQmx is new for LabVIEW RT. I never used it with RT LabVIEW, but with Windows I know it works.

---

Um, I forget when DAQmx was released.  In LabVIEW 7.0, we used "Traditional DAQ" on LabVIEW RT running on a PXI (not PXI-e, yet) system.  When I started updating it (LabVIEW 8-something), I used DAQmx (thank goodness I could dump Legacy DAQ!) on my PXI-based LabVIEW RT system -- I think the final update of this particular Project was in LabVIEW 2014.  Not only does DAQmx work well in Windows, it works even better in LabVIEW RT (well, at least as well ...).

Bob Schor

---

I guess I was thinking of DAQmx on cRIO, which is new.

Sorry.

mcduff

[falcon98]

Is there any efficient way to achieve the maximum acquisition and logging with the PXIe. I am trying but each time the processor cores jump to 100% load.

[mcduff]

---

@falcon98 wrote:

Is there any efficient way to achieve the maximum acquisition and logging with the PXIe. I am trying but each time the processor cores jump to 100% load.

---

Post some code otherwise hard to help.

mcduff