NI DAQ PXie4300 read data

[rakesh@labview]

I want to read 8 ch analog data from an NI DAQ(PXIe 4300) and 8 ch from an Agilent DAQ (M9216). I want one sample of each channel in  2 milllisecond. What is the sampling rate I have to use?. Also Whether I have to use one while loop for both read or to use two while loop for each DAQ?

For Agilent DAQ there is no sampling rate configuration also?

Please help

[Bob_Schor]

Are you kidding?  If you want to read a sample every 2 msec and cannot figure out the sampling rate that you need, you are not ready to start thinking about data acquisition.  Go back to basics, take an introductory Electrical Engineering (or Signal Processing) course, and pay attention in class.

Do you understand your hardware?  You have two PXIe DAQ cards, but connectted to what?  Are they in a single PXIe chassis, or in separate chassis (plural)?  Is the chassis running Windows or a Real-Time OS?

Bob Schor

[rakesh@labview]

That all know bob. sampling rate is 500. I am asking whether I have to use continuous samples or hardware timed single mode.?

Two cards are in in a single PXIe chassis. Also chassis running Windows.

I am asking whether to acquire data from two DAQ cards in single while loop or not?

[Bob_Schor · Accepted solution]

OK, so you are running Windows in the PXIe box.  Do you know how to configure a Task in MAX?  I could configure two Tasks, one for the 4300 and the other for the 9216.  Set both to Continuous Sampling at 500 Hz, set both to the same sample size (say, 500 points, to make the Math easy).

Set everything up before entering the While Loop.  You can put each DAQ in its own While Loop, but let's put them both in the same Loop (you'll see why in a moment).  Come into the Loop with two Error Lines and two Task Lines, and just before entering the Loop, run DAQmx Start Task.

Now, inside the Loop, do a DAQmx Read for each Task, wiring the Sample size (500) to each Read function.  The Principle of Data Flow says that the Loop must complete every function inside before it can "loop", so it will run as fast as the slowest DAQmx Read function (which should be as close to "identical" as their hardware clocks can manage).  Now you have two sets of data to process within a second (the Loop Time) or export to another loop (Producer/Consumer Design).  When you stop the Loop, data acquisition stops for both loops.

Bob Schor

[rakesh@labview]

Thanks Schor.

For NI DAQ card I am able to create task using MAX. But for keysight M9216 how to create task in MAX. Or whether I have to user Keysight libraries. please help

[Bob_Schor]

Sorry, not familiar with the hardware, don't have the software.  Try a Web search, or contact the company.

Bob Schor