Measuring sub 125 microamps using PXI 4110 - Is it possible?

I have a question concerning the PXI 4110. We are trying to use this card to both provide voltage to a device while at the same time using it to monitor the real time current being supplied. What we have found that it is capable of providing voltage from 0 to 6 volts, but have not been able to read below ~500 micro-amps. The data sheet says it has a resolution of 0.01 ma or 10 micro amps, but we have not been able to get the card to read consistently under the 500 micro-amps.
Is there a minimum current draw required before the 10 micro-amp range becomes true?
Here is what we are trying to monitor using this card:
Voltage supplied between 3.5 to 6 volts.
When device is asleep, current draw is between 50 to 100 micro amps.
When device is awake, current draw can be as high as 100 mili-amps.
Will this card work? Is there a better solution to this?
Thanks

Hi John,
Thanks for the additional information. Based on your sampling rate you should be fine with a software or hardware timed device. The answer that you will need to determine is how accurately you need to measure your sleep current. The issue is that you do not know the mode that your DUT will be in to change your current range. At this time our power supplies have output and measure ranges that are coupled together. This means that when you change to a lower range your output current will be limited to the max of that range, which can be an issue when the DUT 'wakes up'.
I would recommend is to select a device that can remain in the higher current range (100mA or greater) and have the measurement capability that meets your needs. You would need to know that you would need to measure the sleep current within +/- X uA. When selecting the device you will then want to look at its measure accuracy on the range you will use. The calculation would be +/- (Measurement*Gain Error + Offset Error). You will find that the largest portion of the error will be offset due to the range you will be using. You also need to take into account the resolution of the instrument because that is the smallest possible change you can measure
One comment on offset error is that for a given test setup/temperature/humidity/etc and test voltage it will stay fairly constant. This means that you can characterize the offset of your system if all of those factors remain constant. I would recommend that you would set up your test, including all fixturing/cabling excluding the DUT. You can set the supply to your test voltage and measure the current. In this setup the ideal current would be 0uA because it is an 'open', but due to leakages in the system there will be an offset. You can take this reading as a baseline 'zero' and subtract it from future readings to improve your measurements. You will want to be careful of Dielectric Absorption (DA) because it can mislead you when making measurements like this, but it is less of an issue when talking about uA and more of an issue when measuring pA. It would be a good idea to repeat this characterization periodically to ensure that your measurements are accurate, ideally once per DUT, but you can scale that back as necessary.
I hope this is helpful. It is a good idea to evaluate the hardware in your test setup to ensure that the measurements meet your needs. I would also add the PXI-4132 to your list of options to consider for its 100mA range. I think that these other devices would be better than the PXI-4110 in your application because of the low current measurements you need. If you can use the additional channels the PXIe-4140/4141 are good options, if not the PXI-4132 would be a good option. You should also consider the different connectors for PXI vs PXIe and what will work for your chassis.
Steve B

Similar Messages

Using PXI 7352 Motion card and 6025E DAQ

Dear Sir,
I am using SCXI 1520 along with PXI 1011 & E Series DAQ (6025E) to measure the Load Value of a load cell. I am also using PXI 7352 Motion card to control the velocity of a Plunger. Now my requirement is to stop the movement of the Plunger depending on the value I read from the load cell. I am not able to achieve the stoping accuracy for high speeds (around 150mm/sec) in the software. Can it be possible with the use of Motion Control card and RTSI signals? If so, how can I do that? (I am not used any limit switches as the load value at which the Plunger should stop is user programmable and I am using DAQ card in Multiplexed mode because i am reading more number of analog inputs with only one DAQ card)
Ramkumar. D
Soliton Automation,
India.

Hello.
Based on your post I am guessing that you are performing the control in software, i.e. starting a velocity move, and then reading the load cell until it reaches a threshold, then stopping the motion. As such you are essentially limited by the software control loop rates.
You are using PXI so it is possible that you are using real-time. If not, one solution could be to implement a real-time application that would be more deterministic, but again this would still depend on the software.
Depending on your system (stepper or servo), you could implement a direct analog feedback into the motion card itself, but this would require a signal which has a range much greater than your load cells. This is only a good option for servo axes. If this was somehow possible, you can tell the motion controller to move to a specified LOAD instead of a specified position/velocity. Provided you could appropriately condition the signal, this is the best choice.
Unfortunately, you cannot implement limit switches/etc over RTSI, so I believe that this will not be a good option.
A third, and probably most un-desireable option, is to output a voltage on the PXI-6025E proportional to the load received from the load cell. This voltage could then be used as the analog feedback for your motion device. This, however, still adds the software layer of delays.
I hope these ideas help you out.
Regards,
Colin C.
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Colin Christofferson
Community Web Marketing
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Triggerring PXI-4110 to measure 1 current value while HSDIO PXI-6552 generating waveform

Hi,
Some question about PXI-4110 to measure current while PXI-6552 is generating the waveform.
1. Let say, I need to measure 3 points of current values, i.e. while PXI-6552 is generating sample-1000, 2000 and 3500. On the edge of sample 1000,2000 and 3500, the PXI-6552 will send a pulse via PFI line or via PXI backplane trigger line. My question is, is it possible to trigger PXI-4110 (hardware trigger or software trigger) to measure current values at these points ?
2. Let say I need to measure the current on 0ms (start of waveform generation by PXI-6552) , 1ms, 2ms, 3ms, 4ms... and so on for 1000 points of measurement, code diagram as shown at the figure below. It is possible for the VI "niDCPower Measure Multiple" to measure exactly at 1ms, 2ms, 3ms .. ? How much time will have to spend to complete acquire 1 point of measurement by "niDCPower Measure Multiple" ?
Thanks for viewing this post. Your advice on hardware used or software method is much appreciated. Thanks in advance.
Message Edited by engwei on 02-02-2009 04:24 AM
Attachments:
[email protected] ‏46 KB

Hi engwei,
1. Unfortunately, the 4110 does not support hardware triggering. Therefore you cannot implement direct triggering through the backplane or anything like that. However, there are a couple of possible workarounds you can try:
a) Use software triggering: Say your 6552 is generating in one while loop, and your 4110 is to measure in another while loop. You can use a software syncrhonization method like notifiers to send a notification to your 4110 loop when your 6552 has generated the desired sample. This method, however, will not be very deterministic because the delay between the trigger and the response depends on your processor speed and load. Therefore, if you have other applications running in the background (like antivirus) it will increase the delay.
b) Use hardware triggering on another device: If you have another device that supports hardware triggering (like maybe an M-series multifunction DAQ module), you can configure this device to be triggered by a signal from the 6552, perform a very quick task (like a very short finite acquisition) then immediately execute the DCPower VI to perform the measurement. The trigger can be configured to be re-triggerable for multiple usage. This will most likely have a smaller time delay then the first option, but there will still be a delay (the time it takes to perform the short finite acquisiton on the M-series). Please refer to the attached screenshot for an idea of how to implement this.
2. To make your 4110 measure at specific time intervals, you can use one of the methods discussed above. As for how long it will take to acquire 1 measurement point, you may find this link helpful: http://zone.ni.com/devzone/cda/tut/p/id/7034
This article is meant for the PXI-4130 but the 4110 has the same maximum sampling rate (3 kHz) and so the section discussing the speed should apply for both devices.
Under the Software Measurement Rate section, it is stated that the default behavior of the VI is to take an average of 10 samples. This corresponds to a maximum sampling rate of 300 samples/second. However, if you configure it to not do averaging (take only 1 sample) then the maximum rate of 3000 samples/second can be achieved.
It is also important to note that your program can only achieve this maximum sampling rate if your software loop takes less time to execute than the actual physical sampling. For example, if you want to sample at 3000 samples/second, that means that taking one sample takes 1/3000 seconds or 333 microseconds. If you software execution time is less than 333 microseconds, then you can achieve this maximum rate (because the speed is limited by the hardware, not the software). However, if your software takes more than 333 microseconds to execute, then the software loop time will define the maximum sampling rate you can get, which will be lower than 3000 samples/second.
I hope this answers your question.
Best regards,
Vern Yew
Applications Engineer, NI ASEAN
Best regards,
Vern Yew
Applications Engineer
Attachments:
untitled.JPG ‏18 KB

How to Measuring the Temperature of the PXI-1045 Controllers Using LabVIEW

Hi,
I need to continuously monitor the temperature of the PXI-1045 controller. I have had a look the vi supplied by NI on http://zone.ni.com/devzone/cda/epd/p/id/4538#0requirements which is developed for PXI-8196/95 and the PXI-8186/87 controllers. Can similar temperature measurement be done on PXI-1045?
Regards
Mehran

Hi Mehran,
Sorry, but those aren't controllers either! Controllers are the 2- and 3-slot cards that act like the computer in your PXI system. They will generally have a model number of 81xx. For information on our PXI controllers, have a look at http://sine.ni.com/nips/cds/view/p/lang/en/nid/1534. When you measure the temperature of your PXI controller, you're measuring the temperature on the CPU - this is something you can do on almost any PC.
Chassis and PXI devices do not have CPUs with thermistors to measure the temperature, so you can't read the temperature. Again, if you want to determine the ambient chassis temperature you'll need to use a thermocouple or something similar.
Regards,
Tom
Applications Engineering, NI UK

Measure power/current being delivered by PXI-4110 on a specific channel?

I have a PXI-1033 chassi and inside it there's a PXI-4110. How do I use LabVIEW 8.2.1 to determine the power/current consumption on a specific output channel?

I have a PXI-1033 chassi and inside it there's a PXI-4110. How do I use LabVIEW 8.2.1 to determine the power/current consumption on a specific output channel?

Accurate frequency measurement using PXI 5142 Digitizer

I am Using PXI 5142 Digitizer to read the frequency of a 10 MHz atomic clock up to 8 decimal places. I am using single tone measurement block. But I can't get that accurate fix on the frequency because of the jitter.
Can someone help.
Thanks in Advance.

Thanks For your reply; The device is connected to the digitizer through BNC connector.
Digitzer Scope Settings:
Samples/seconds --> 2G S/s
Record Length      --> 800
Aqiusition mode   ---> N Samples
Best Regards,
Helal
Attachments:
Block Diagram.JPG ‏117 KB
Front Panel.JPG ‏91 KB

What is the proper way to close all open sessions of a NI PXI-4110 for a given Device alias?

I've found that, when programming the NI PXI-4110 that, if a the VI "niDCPower Initialize With Channels VI" (NI-DCPower pallette) is called with a device
alias that all ready has one or more sessions open (due to an abort or other programming error) a device reference results from the reference out that has a (*) where "*" is post-fixed to the device reference where and is an integer starting that increments with each initialize call. In my clean up, I would like to close all open sessions. For example, let's said the device alias is "NIPower_1" in NI Max, and there are 5 open sessions; NIPower_1, NIPower_1 (1), NIPower_1 (2), NIPower_1 (3), and NIPower_1 (4). A simple initialize or reset (using niDCPower Initialize With Channels VI, or, niDCPower Initialize With Channels VI, etc.) What is the proper way to close all open sessions?
Thanks in advance. Been struggleing with this for days!

When you Initialize a session to a device that already has a session open, NI-DCPower closes the previous session and returns a new one. You can verify this very easily: try to use the first session after the second session was opened.
Unfortunately, there is a small leak and that is what you encountered: the previous session remains registered with LabVIEW, since we unregister inside the Close VI and this was never called. So the name of the session still shows in the control like you noted: NIPower_1, NIPower_1 (1), NIPower_1 (2), NIPower_1 (3), and NIPower_1 (4), etc.
There may be a way to iterate over the registered sessions, but I couldn't find it. However, you can unregister them by calling "IVI Delete Session". Look for it inside "niDCPower Close.vi". If you don't have the list of open sessions, but you have the device name, then you can just append (1), (2) and so forth and call "IVI Delete Session" in a loop. There's no problem calling it on sessions that were never added.
However - I consider all this a hack. What you should do is write code that does not leak sessions. Anything you open, you should close. If you find yourself in a situation where there are a lot of leaked sessions during development, relaunching LabVIEW will clear it out. If relaunching LabVIEW is too much of an annoyance, then write a VI that does what I described above and run it when needed. You can even make it "smarter" by getting the names of all the NI-DCPower devices in your system using the System Configuration or niModInst APIs.
Hope this helps.
Marcos Kirsch
Principal Software Engineer
Core Modular Instruments Software
National Instruments

How to count number of edges using PXIe-6363 Counters

Hello,
I am trying to count number of edges in a test signal in a 50 ms duration. I am using PXIe-6363 card and connecting the test signal to CTR 0 SRC (PFI 8). Is it a correct connection? What else do I need hardware-wise to make a correct set up for this application?
Thanks
Jeet
Solved!
Go to Solution.

Hi Jeet,
When you say interrupt signal, do you mean a pulse that will pause your counter task? If that is the case, and you want to pause your task with a digital pulse, you need to use the DAQmx Trigger Property Node and set that to Pause, Trigger Type. As you said, you can connect that signal coming from the chip to any PFI line and then set that line as the source of the property node.
There is an example that you can use that does exactly what I just described. This example is called Count Digital Events-Pause Trig.vi, and you can find it by going to Help>Find Examples..., then on the NI Example Finder window go to the Browse tab and navigate in the folders to Hardware Input and Outpout\DAQmx\Counter Measurements\Count Digital Events.
Regards.
Jorge
Applications Engineer
National Instruments
Certified LabVIEW Associate Developer (CLAD)

I have been trying to pass a controlling signal out of a running sub vi to start a case sequence that contains a measurement sub vi. I can't get it to work,can anyone help me.

I have tried several different means of getting a controlling signal out of gl_flicker_vi. What I want is to pull the current iteration value out of the inner while loop, compare that to another value and if true, trigger the case structure that contains the Take measurements sub vi. I can get an indicator on the main vi to register the iteration values from the sub vi, but I can't use them to control the case structure. When I connected a reference to the control and then a property node within the sub vi, I alway end up with broken wires. Is there anything that I can do to
get values out of the sub vi that I can use for my purpose? Is there something that I don't know about using references and property nodes that I should at this point? Any help would be greatly appreciated.
Attachments:
GL_Flicker_mod.vi ‏88 KB
Take_Measurements.vi ‏147 KB
Pass_a_Reference.vi ‏69 KB

1-Apparently, you didn't wire an input for your DigNum Refnum, the ref to the inner loop index. That's where your broken wire should connect.
2- Better now : you could create a global variable of the loop index, that you can read anywhere in LabVIEW.
3- Anyway, your vi will not behave the way you want, since your comparison node will be operated by LabVIEW before anything comming back from GL-Flicker. Use a loop there ?
I think that you are a overusing propertie nodes, and I believe that there is probably a better and simpler way of doing what you want here...
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

IVI Configuration with PXI-4110 in TestStand

Hello All,
Set-Up:
PXI-1033 connected through MXI to a PC running Windows 7. LabVIEW 2014. TestStand 2014 (32-bit). PXI-4110 Power Supply and PXI-4070 DMM.
In MAX I can open both soft panels and control both units and they work great. In LabVIEW I can control both cards as well.
In MAX I have set up a driver and logical name for my DMM. This unit works great within TestStand using an IVI DMM step.
I then proceeded to setup the 4110 in MAX with an IVI driver and logical name. Here are my settings:
Name: ni4410_PS
Hardware: Added hardware asset and select the PS. This one is checked, no other assets are checked.
Software Module: NI-DCPower, 4110 is listed as a device that is supported.
Virtual Names: This is where I am confused, Under physical name there are four options that come up (0, 1, 2, and 3). This power supply only has 3 outputs so I am unsure why four come up. I have made 4 virtual names, one for each of the options. I named them ch0, ch1, ch2, and ch3 respectively.
When I put an IVI Power Supply step in TestStand everything seems to be working. I open the configuration window and set my values for each channel. If I try to validate the setup by unchecking simulate and click on init I do not get an error. As soon as I clic on 'Configure' or 'Show Soft Front Panel' I get the following error:
"The IVI Configure operation failed for lgical name 'NI PS 1'. Details: Extention capability not supported by instrument driver. (Base) (-30717)"
Any information would be appreciated. I tried playing with it for a couple hours yesterday and had a couple co workers try to help. We are all under the assumption that this should be working.
Thank You!!
Jesse
Solved!
Go to Solution.

Hi jesserzamora,
Have you seen this link: http://digital.ni.com/public.nsf/allkb/331F2717DBCD1F858625758200745773?OpenDocument
It discusses a similar failure with the IVI Power Supply step in TestStand.
Julia P.

Pxi 4110 and dcpower express vi

hi everyone,
I'm really new to labview and I have to use a pxi 4110 to supply dc voltage with a square wave (or whatever shape I chose).
I treid using the "dcpower express vi" but I can't understand how to connect the generated signal. at now I have the wave and I put a block which transforms the wave from dynamic data to array.. but it doesn't work!
i tried watchin g the examples, but none of them uses power express...
thanks for any help!!

As bronzacuerta mentioned, the PXI-4110 is not intended to generate a square waveform, or any specific waveform. It is intended to regulate a constant voltage or current, adjusting for changing loads. By changing the output using the NI-DCPower API, you may be able to approximate a square waveform, but it will not be a very good one, both in terms of rise/fall times and due to software-timed output updates.
A potentially better option (based on speed/flexibility/accuracy requirements) instead of a Multifunction DAQ card is a signal generator.
Tobias
Staff Software Engineer
Modular Instruments
National Instruments
Tobias
Staff Software Engineer
Modular Instruments R&D
National Instruments

NI DC Soft Front Panel, minorbug, minor bug with PXI-4110

Hi
The NI DC Soft Front Panel V14.0, with the PXI-4110, the negative voltage scroll, works as expected to -10V, but then rolls over to 0. If one changes in -1V steps, it goes.... -8, -9, -10, -1, -2 ..... instead of -8, -9, -10, -11, -12 ...
While at it, a simple thing I miss is a on/off button for all three voltages.
(Also, imo, it would be logical to get negative voltages with the down arrow, not up).
My 2C
Solved!
Go to Solution.

Hello Janaf,
I fully agree with both of your statements, I have filed a Correction Action Report which you can monitor in next releases of DCPower to see if this is fixed with the SFP. Number of CAR: 512257
I added notes that only manual insertion of numbers less than -10 works and that it was not logical to use increment arrow or up arrow to decrease the voltage output.
Best Regards
Jonas Mäki
Applications Engineering
National Instruments

PXI-4110 Cards failing since upgrading to Calibration Executive 3.4

Since we upgraded to Calibration Executive 3.4 all of our PXI-4110 Cards have been failing the following:
Calibration
As Found
Channel
As Found DMM Reading
As Left DMM Reading
Test Value
Low Limit
Reading
High Limit
PassFail
2
0.999942
A
0.999942
A
0.25000
A
0.99557
A
0.94065
A
1.00432
A
Failed
2
0.999991
A
0.999991
A
0.50000
A
0.99524
A
0.93736
A
1.00474
A
Failed
2
0.999761
A
0.999761
A
0.75000
A
0.99370
A
0.94076
A
1.00582
A
Failed
This failure occurred on 3 brand new cards and I have even tried the last PXI-4110 before upgrading and it also failed these test and when an adjustment is attempted I receive the following error:
Error -300010 occurred at Get UserField Data.vi
Complete call chain:
     cex_UtilityGetUserFieldData.vi
     cex_UtilityGetUserFieldDataByIndex.vi
     _NI 4110_Get Channel Range and Level.vi
     Adjust_NI 4110_Current Out Accuracy.vi
at step Adjust Current Output Accuracy
I am using a Agilent 34401 for the DMM.

JVP
Here are the files you wanted. Sorry this took so long. The hard drive on the computer that we have the Calibration Executive software on died and we had to reinstall everything. So and I tried to run another card with the same results the calibration report I am sending you is from today. I sent the reoprt in two formats XLS and PDF.
Attachments:
ni_support.zip ‏197 KB
71517 Wednesday, January 11, 2012 8-28-29.xls ‏49 KB
71517 Wednesday, January 11, 2012 8-28-29.pdf ‏30 KB

PXI-4110 niDCPower_init

I am just starting to write a program for my PXI-4110 Programmable DC Power Supply.
I am using the function niDCPower_init(). When I read the documentation about this function it made this statement:
"This function is deprecated. Use niDCPower_InitializeWithChannels instead."
My fp file (nidcpower.fp) does not have this function. Do I need a newer fp file? Is this function niDCPower_init() only a poor choice or is there something wrong with it?
Deprecated was an odd word to use to describe this function. It implies that the function is disapproved of but maybe it works. What is the opinion of others?
I am going to try it out but would like to know if this is the function I want to use.
thanks in advance

DPearce,
Thank you for using NI forums! Deprecated functions use the deprecated programming model.
In terms of the niDCPower_init function, it is obsolete. If you do not have niDCPower_InitializeWithChannels, I would recommend downloading the most current version of our driver. You can download the driver here. You can find more information on this function here. The VI version is here (I tend to find the VI version a little more reader friendly!).
Also, I would check out the shipping examples that come with this driver. That will help you see the various functions in action and assist you in determining which one you want to use.
Let me know if you have any other questions!
Katie
Katie Collette
National Instruments

Conflict between the saved data and the sampling rate and samples to read using PXI 6070e

Hello, I am using PXI 6070e to read an analog voltage. I was sampling at 6.6 MHz and the samples to read were 10. So, that means it should sample 10 points every 1.5 um. The x-axis of the graph on the control panel was showing ns and us scale, which I think because of the fast sampling and acquiring data. I use "write to measurement file" block to save the data. However, the data was saved every 0.4 second and as 35 points data at the beginning of each cycle (e.g. 35 points at 0.4 sec and 35 at 0.8 sec, and so on) and there was no data in between. Can anyone help me how there are 35 reading points every cycle? I could not find the relation between the sampling rate and samples to read, to 35 points every 0.4 second!
Another thing, do I need to add a filter after acquiring the data (after the DAQ assistant block)? Is there anti-aliasing filter is built in PXI 6070e?
Thanks for the help in advance,
Alaeddin

I'm not seeing anything that points to this issue. Your DAQ is set to continuous acquire. I'm not sure if this is really what you want because your DAQ buffer will keep overwriting. You probably just want to set to Read N Samples.
I'm not a fan of using the express VIs. And since you are writing to a TDMS file, I would use the Stream to TDMS option in DAQmx. If you use the LabVIEW Example Finder, search for "TDMS Log" for a list of some good examples.
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Measuring sub 125 microamps using PXI 4110 - Is it possible?

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