Real Time ADC/DAC for SMPS using Labview and USB

[rt54321]

Hello all,

I have asked the sales department this same question, so here's a two-pronged approach:

I am reserching a control algorithm for a switch-mode power supply, and so far, the simulations for its performance look good.  Now, the goal is to implement the circuit for experimental data.

I've seen several NI USB DAQ boxes that appear to have the performance I'm looking for (for example, the USB-6211 would have the resolution and sampling rate that I need).

The control algorithm uses the following math functions:  add/sub/mult/div/exponent, and derivative/integral.

My question is this: is Labview "strong" enough to take in four channels of 250Ksps data, crunch the numbers in an equation, and spit out the answer to an analog out channel, all in REAL time?  I'm looking for an analog output rate of ~100kHz.

Thank you for any suggestions that you have!

-Rick

[sparkysquared · Accepted solution]

Hey,

So if you were just trying to perform an input or output then the USB-6211 would certainly be able to handle it because the hardware clock would be handling the input/output, not software. However, what you're wanting to do, basically a feedback system, will require software timing (at least for a USB device) because you'll have to be able to actively specify what the output is. So, for that reason alone, and the fact that you want 100kHz output, this device and USB devices in general won't be an option no matter what software you use, LabVIEW or otherwise. On another note, what you're looking to do sounds more like live updating, not Real-Time, which is more about jitter. Bottom line, for these kinds of requirements, you're going to need to move to an FPGA board, something like the NI PCIe-7841R would work. It's more expensive, but for your requirements, FPGA is going to be the only option and it comes down to bus latency as well as software response time. With FPGA, as is shown in the first diagram of the following document, you're basically closing your software loop through hardware.

FPGA Fundamentals

http://www.ni.com/white-paper/6983/en

--Ryan S.

[srm@viewpointusa.com]

Ryan is correct.  LabVIEW FPGA is the solution from NI.  you can also look at the cRIO platform.

We have implemented solutions like you describe with both PXI and cRIO FPGA.

[rt54321]

Thank you BOTH for your comments!

-Rick