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NI-DCPower package, sample rate

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Hi,

 

We use NI-DCPower package to communicate with PXIe-4144, PXIe-4138, etc. Surprisingly I cannot fund how the sample acquisition rate can be set with this package.

 

The answer is probably too simple to bee found easily Smiley Happy

 

Please advice

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www.azinterface.net - Interface-based multiple inheritance for LabVIEW OOP
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I don't have this hardware (or software) installed, and can't find the manuals on-line.  However, I did find the following:

 

You can acquire data interactively using the NI-DCPower SFP or programmatically using the NI-DCPower instrument driver in your application. You can also run the NI-DCPower examples to demonstrate the functionality of the power supply or SMU. Acquiring Data Interactively Launch the NI-DCPower SFP from Start»All Programs»National Instruments»NI-DCPower» NI-DCPower Soft Front Panel. The NI-DCPower SFP provides context-sensitive help for its controls.

 

Acquiring Data Programmatically

 

You can use NI-DCPower to begin programming the NI power supply or SMU in your ADE. For detailed instructions about how to acquire data in a specific ADE, refer to the Getting Started section of the NI DC Power Supplies and SMUs Help located at Start»All Programs»National Instruments»NI-DCPower»Documentation»NI DC Power Supplies and SMUs Help» Programming»Getting Started.

 

NI-DCPower Examples

 

Examples demonstrate the functionality of the device, serving as programming models and building blocks for your own applications. The NI Example Finder is a utility available for some software applications that organizes examples into categories and allows you to easily browse and search installed examples. You can see descriptions and compatible hardware models for each example or see all the examples compatible with one particular hardware model. To locate examples, refer to the following table. Software Application Locating Examples LabVIEW or LabWindows/CVI Locate examples with the NI Example Finder. Within LabVIEW or LabWindows/CVI, select Help»Find Examples and navigate to Hardware Input and Output»Modular Instruments» NI-DCPower (DC Power Supplies).

 

Bob Schor

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Hi _Y_

 

What do you mean by sample acquisition rate?  Those are SMUs, not DAQs.  Yes, you can do sweeps/sequences and get multiple data points back at once but you generally don't talk sampling rate with SMUs.  

 

You can reduce the time per measurement using the "Aperture Time" VI or the Property node Property Node for "Measure > Aperature Time".  (If you are using sequences there's a VI to configure advanced sequence properties or sequence delay times.) 

 

However, the true speed of the measurement for an SMU depends on lots of factors, source delay, averaging, auto-ranging, auto-zeroing, aperture time, and the actual range of the I/V being sourced and the range of the I/V being measured (i.e. usually the smaller the I/V the longer it takes to reliably source or measure). So you will want to consider all of these factors when setting up your measurement if speed is a consideration.  

 

Craig

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Thank you for replies. If I understand you correctly, there is no way to implement HW timing; i.e. the timing must be controlled at SW side.

 

However, I should probably explain our needs. May be there is some smarter way.

 

We set voltage or current and request voltage/current values (IV) from SMU device. However, the values of interest are not instant; so we read IV countinuously waiting for stable state. So far so good, as long as we need only final (stable) IV. However, we also need the curve - history of IV change from set time to time of stabilisation. I was thinking that HW timing wold probably be a better solution.

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Have a look at the NI-DCPower Example "Measure Record.vi".  Use the Exaple Finder to search for Power and it will come up part way down the list.  This seems to be exactly what you are describing and shows how to set aperture time and use HW timing to gather multiple points in succession for a fixed voltage bias.

 

Craig

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Thank your cstorey. Yes indeed this example can help.

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