Pxi-4071 shielding cable

Hi, we use pxi-4071 on pxi-1033 for measurments and we connected shielded cables few meters long. We wrapped foil cables from the kit. After that we connected all the shields to the ground from the power supply. But we still remain interferences about 1nA and DC component 5nA. If anyone faced a similar problem, is it possible that we are too often measured current. Can you advise the shilded cables for multimeter in this case.

alyast wrote:
Yes, we pretty sure in shielding, but we don't know why there is current constant component (5nA), while declared sensitivity - 0.1nA. Probably some bug with timing in LabView or something? I don't know what could be a reason for this behavior, and therefore ask noob questions.
Why would you suspect the software when all the evidence points to an issue with the HARDWARE? And if you're measuring in the nanoAmp region, you'd better be ABSOLUTLEY certain that your grounds are true and accurate. Probably grounding to your power supply is not good enough. Your power supply probably has to be grounded to a copper stake going - what is, it, six feet? - into the ground.
Bill
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.

Similar Messages

Pxi-4071 constant current

We use 4110 voltage source for current measurements on pxi-4071. We supply high-ohm (1.5 GigaOhm) resistor with few volts and measure current on 4071. All cables are shielded on ground of 4110 voltage source, but cables are about 5 meters long. What can be reason for constant current 5 nA at zero supply voltage? We don't know whether it software or hardware problem, and i already asked this question in LabView forum, autozero enabled in max doesn't help. Could be a reason bad shielding of ground in pxi-4110 voltage source

I would focus on the hardware side initially. I would try the following steps.
1) Make a current measurement on the 4071 with the inputs open to see if there is an offset. If so we should look into the DMM configuration.
2) Connect your cabling and/or resistor without the 4110. If this adds the offset then it seems to be shielding/noise related.
3) Connect the cabling and/or resistor to the 4110 with the output disabled. If this adds the offset then it could be ground related or also related to an offset in the 4110 output.
Steve B

How to acquire data through multiple channels in parallel using PXI 6070 E, PXI 4071 and LabVIEW?

Hi,
I am using NI LabVIEW, NI PXI 4071, and NI PXI 6070E to measure current through a variable resistance. Now, I am using one channel from SCB-68, but I want to add another channel in parallel so that I can have two resistors instead of one that I cam measure current through them.
I have attached a Pdf file showing the setup for hardware in use and LabVIEW code also.
Can anyone look at these files and give me guide lines or ideas that can help me resolving this issue, please.
Thanks in advance.
Best Regards,
Shaheen.
Solved!
Go to Solution.
Attachments:
IV copy for HS.vi ‏55 KB
Layout of NI Cards.pdf ‏248 KB

Your 4071 can only do one measurement at a time. Your DAQ cannot measure resistance either nor has it got any analogue inputs.
However, you could use a multiplexer and multiplex your 4071 DMM. This wont give you simultaneous measurements but can acquire data one after the other, the speed is obviously dependent on the multiplexer you choose!
Hope this helps.
Beginner? Try LabVIEW Basics
Sharing bits of code? Try Snippets or LAVA Code Capture Tool
Have you tried Quick Drop?, Visit QD Community.

Setting Input Resistance on the PXI-4071

The specifications for the PXI-4071 DMM indicate that the input resistance can be chosen as either 10 MOhm or 10 GOhm for the 100 mV, 1 V, and 10 V ranges. I see where this can be input on the instrument soft panel, but I have been unable to locate how to configure the input resistance when using the DMM in a VI. Suggestions?
Thanks!
Jeff
Jeffrey Zola
Solved!
Go to Solution.

You need to use a property node.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
Attachments:
input resistance.png ‏13 KB

Pxi-4071 aux I/O how to output a control signal?

HI, I am working on Pxi-4071 dmm card. I want to use aux I/O to out put a control signal for a relay on/off. Technically, I want to know how to do it with labview. Is any examples to start?
Thanks
Liming

Hello Liming,
The DMM is capable of sending TTL triggers out on both the PXI_Trig lines and on the AUX connector on the front connection. These signals are intended for controlling National Instruments switch modules and not powering/closing third party relays.
If you're looking to control a National Instruments Switch there are example programs that demonstrate synchronous scanning with DMMs and Switches. To locate these examples open LabVIEW and go to Help» Find Exampled... Then Navigate to Hardware Input and Output» Modular Instruments» NI-Switch (Switches).
If this isn't what you're looking to do, or if you have additional questions, please feel free to post back with more information.
Have a great weekend!
Brooks

Error -1074118625 with PXI-4071 and PXI-2527

When using the LabVIEW IVI drivers for PXI-4071 and PXI-2527, I receive an error -1074118625 in TestStand. The sequence initializes the MUX, init DMM, connects the MUX, waits for debounce, and then upon reading from the DMM, I receive this error.
Error: niDMM Read Waveform (waveform data).viExplanation could not be found for the requested status code.
Verify that the requested status code is correct.
[Error Code: -1074118625, User-defined error code.]
This sequence of events is successfully used multiple times elsewhere in the TestStand. This error does not appear in any knowledgebase article nor in any help. Any explanation would be greatly appreciated.
Solved!
Go to Solution.

I found this with google that seems like it might apply:
http://digital.ni.com/public.nsf/allkb/A593DEBFD86A69C68625727900748EEC

Measure Power using Labview and two PXI-4071 DMMs

Hello,
I am trying to make a simple VI. I am measuring input AC voltage and Current using two PXI-4071 DMMs. I want to Calculate Power and Power Factor. I am able to read the voltage and current fine. I just dont know how to calculate the power and power factor. Im looking for real power not watt*amps. Please Help.
Scott
Attached is my VI
Attachments:
Measure AC Voltage and Current.vi ‏42 KB

Scott,
It appears that another applications engineer (Sean_N) has been assigned your initial forum post. I assure you that he is working on finding an answer to your question. We would like for our customers to limit questions to one forum so that we do not duplicate efforts on our end. I will contact Sean to remind him that you are awaiting a response. I will also point all future traffic from this post to your initial one.
Thanks,
Kareem W.
National Instruments
Web Product Manager

Pxi-4071 ranges

Why is it so hard to find the ranges for the PXI-4071??????? I called National and they told me:
The ranges that are possible to use are:
+-.02
+-.20
+-2
+-25
+-250
Yet when I open the soft front panel there is a range up to 1000 volts. Where is this listed?? I need ranges for VDC, current dc and resistance ( opens...infinite) I'm using the DMM drivers that ships w LV 8.6.
Thanks

All of the range specifications will be found in the PXI-4071 user guide and specifications document.
If you search on ni.com for 4071 you will find the PXI-4071 product page. Going to the specifications tab, and then clicking "detailed specifications" opens this document. It contains all of the specifications and accuracy ratings of the device.
NI 4071 Specifications (Multilingual)
Page two specifies that for DC voltage the following are valid ranges:
100mV
1V
10V
100V
1000V
which also show up in the DMM soft front panel.
For DC current, see page 4, which states
1uA
10uA
100uA
1mA
10mA
100mA
1A
3A
Resistance, page 5,
100Ohm
1kOhm
10k
100k
1M
10M
30M
100M
5G
Thse pages also have the charts for the accuracy of the DMM at each one of these ratings.
Eric S.
AE Specialist | Global Support
National Instruments

Pxi-4071 error on calibration executive

hi!
i have this little problem with my NI calibration executive. The error says
" Error-1071001424 occurred at Error-1071001424 occurred at ***configcalibratorandwait.vi
Possible reason(s)
Current Compliant Voltage Exceeded".
Can you guys help me on this? I am calibrating this NI DMM PXI-4071. Please see attached captured error.
thanks.
ating

popoi,
Thanks for posting on the NI forums. I have a couple questions for you that should help us get to the bottom of the problem.
What version of Calibration Executive are you using? You should be able to find this by going to the Help Menu >> About Calibration Executive.
What Equipment are you using to perform the calibration? There is a list of equipment here.
Is this the only board that you are having difficulty calibrating with Calibration Executive?
Thanks!
Aaron W.
National Instruments
CLA, CTA and CPI

Why would a PXI 4071 measuring resistance countinue to increase the measured valued for each measurement?

I have a PXI-4071 DMM and I am measuring a connection in the UUT. The value should be around 0.3 ohms. The program (exe) will run aprox. 20 times and during these 20 runs the measured value will progressively increase until is is over the limit of 1.5 ohms. If I shut down the exe and run the VI as a standalone (continuous loop), the resistance will gradually come down to 0.3 ohms. I then close LabView and restart my exe and the readings are normal (0.3) but then continue to increase until they are over 1.5 ohms. This process has been repeatable for the last week. I have attached the code I am running. What could be the problem with the DMM code?
Attachments:
DMM_MeasResistance2.vi ‏64 KB

Uninitialized shift registers are a good thing to check for such a problem. Do you see the same response with a soft panel and your DMM? if not then it is in code. Uninitialized shift registers would start at 0 (default is usually 0) and will retain their values from run to run. Just a possibility dont have LV up right now so I cant check the code sorry,
Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

PXI 4071 error

你好：
我有一张PXI-4071的DMM ,用MAX的NI-DMM SOFT FRONT PANEL程序时，显示OVLD V DC,正常的都是.显示数值0.00000000 V DC，请问这是什么引起的？是这张卡坏了吗？

DMM线都没接，没有量测动作的时情况下，打开程序就直接OVLD,如下图所示
附件:
PXI DMM-4071.PNG ‏73 KB

Setting up the sample rate on a PXI-4071

I am new to this and hoping that some one can help...
I have a DC power supply connected to a PXI-4071 that I am attempting to get some stable DC voltage measurements using LabView but
the measeurement values are all over the board so I am guessing that I am missing some sort of sample rate set up.
Any suggestions?
Thanks
Attachments:
My VoltageRead.vi ‏30 KB

I figured it out..
I had my constant "2" wired to the function instead of the resolution...

Crosstalk problem with shielded cable on 6509.

Hi,
I've got an interesting problem with my 6509 test setup. I have the 6509, an SH100100-Flex cable, and the SCB100 shielded connector block. The problem occurs when I configure one line for output and, on a separate port, configure other lines (adjacent to the output line) for input.
Without the cable connected, when I look at the logic on the input lines, they do not mirror the output. With just the cable connected (i.e. no connector block) the input lines seem to be mirroring (that is, have lots of crosstalk) with the output line. However, when I measure the impedance on the pins it is overload. Finally, of course, with the connector block, I have the exact same issue. Does anyone understand what is happening? How do
I prevent this crosstalk? Do you think the cable is not working correctly?
Thanks!

Hi 6509User,
Since the input impedance of the 6509 is high, and you don't have any other device driving those inputs, then those lines are essentially floating. In this configuration, those lines a very susceptible to crosstalk. Adding the cable allows the inputs to become AC coupled with the adjacent ouptput lines.
Go ahead and connect an output from your device to the 6509's input lines. Once the lines are being driven either high or low, I suspect that the majority of the crosstalk will go away.

Analog multichannel shielded cable

We need to connect a multichannel sensor to our intermediate board (before NI xseries digitizer). The intermediate board will be custom designed, it can have virtually any connector.
Sensor has 32 channel connector (mating is MS3116F20-41S). We could not find a good cable for it (see signal description below), so we need to make a custom connection.
Our idea is to take a good cable, cut it and solder a connector for the sensor on free end.
Signal from the sensor: 0.5 us, pulses 30uV - 5 mV amplitude with ~1 V bias offset, up to 10 kHz rate.
Sensor is a ~100 Ohm resistance, so current is 10 mA average on each channel.
Signal is AC coupled, amplified, integrated on our board, so pulse shape change is not important. Distance is up to 1 m (3 feet). We can not place ac coupling and amplifier closer to the sensor.
Pulses on all channels happen at the same moment, cable should not allow cross-talk at least up to 1/1000.
Surrounding environment is pretty noisy.
The questions are: what type of shielding is recommended, should each channel be individually shielded?
What cable would you recommend?
Thanks in advance!

Alexander_Sobolev,
Sounds like a challenging measurement problem!
I would probably use a multi-pair twisted cable with each pair individually shielded. Something like Alpha Wire 6019C. Since your cable is short and the currents are small, you could probably use a cable with smaller wires than that example. Apparently the sensor outputs share a common or ground since the connector does not have enough contacts for a pair of conductors per channel. I would probably ground one wire of each pair at both ends and ground the shields only at one end. If ground loops are a possibility, build some isolation into the intermediate board.
At the intermediate board I might use a DB-50 connector with a metal shell. Ground as many of the pins as you can and connect the shell to the shields. Put good mechanical supports on the connector on the board and use jack screws to hold the cable to the board.
Lynn

PXI 2527 & PXI 4071 -Questions about EMF considerations for high accuracy measurements and EMF calibration schemes?

Hi!
I need to perform an in-depth analysis of the overall system accuracy for a proposed system. I'm well underway using the extensive documentation in the start-menu National Instruments\NI-DMM\ and ..\NI-Switch\ Documenation folders...
While typing the question, I think I partially answered myself while cross-referencing NI documents... However a couple of questions remain:
If I connect a DMM to a 2 by X arranged switch/mux, each DMM probe will see twice the listed internal "Differential thermal EMF" at a typical value of 2.5uV and a max value of less than 12uV (per relay). So the total effect on the DMM uncertainty caused by the switch EMF would be 2*2.5uV = 5uV? Or should these be added as RSS: = sqrt(2.5^2+2.5^2) since you can not know if the two relays have the same emf?
Is there anything that can be done to characterize or account for this EMF (software cal, etc?)?
For example, assuming the following:
* Instruments and standards are powered on for several hours to allow thermal stability inside of the rack and enclosures
* temperature in room outside of rack is constant
Is there a reliable way of measureing/zeroing the effect of system emf? Could this be done by applying a high quality, low emf short at the point where the DUT would normally be located, followed by a series of long-aperture voltage average measurements at the lowest DMM range, where the end result (say (+)8.9....uV) could be taken as a system calibration constant accurate to the spec's of the DMM?
What would the accuracy of the 4071 DMM be, can I calculate it as follows, using 8.9uV +-700.16nV using 90 days and 8.9uV +- 700.16nV + 150nV due to "Additional noise error" assuming integration time of 1 (aperture) for ease of reading the chart, and a multiplier of 15 for the 100mV range. (Is this equivalent to averaging a reading of 1 aperture 100 times?)
So, given the above assumptions, would it be correct to say that I could characterize the system EMF to within 8.5uV+- [700.16nV (DMM cal data) + 0.025ppm*15 (RMS noise, assuming aperture time of 100*100ms = 10s)] = +-[700.16nV+37.5nV] = +- 737.66nV? Or should the ppm accuracy uncertainties be RSS as such: 8.5uV +- sqrt[700.16nV^2 + 37.5nV^2] = 8.5uV +-701.16nV??
As evident by my above line of thought, I am not at all sure how to properly sum the uncertainties (I think you always do RSS for uncertainties from different sources?) and more importantly, how to read and use the graph/table in the NI 4071 Specifications.pdf on page 3. What exactly does it entail to have an integration time larger than 1? Should I adjust the aperture time or would it be more accurate to just leave aperture at default (100ms for current range) and just average multiple readings, say average 10 to get a 10x aperture equivalent?
The below text includes what was going to be the post until I think I answered myself. I left it in as it is relevant to the problem above and includes what I hope to be correct statements. If you are tired of reading now, just stop, if you are bored, feel free to comment on the below section as well.
The problem I have is one of fully understanding part of this documenation. In particular, since a relay consists of (at least) 2 dissimilar metal junctions (as mentioned in the NI Switch help\Fundamentals\General Switching Considerations\Thermal EMF and Offset Voltage section) and because of the thermo-couple effect (Seebeck voltage), it seems that there would be an offset voltage generated inside each of the relays at the point of the junction. It refeers the "Thermocouple Measurements" section (in the same help document) for further details, but this is where my confusion starts to creep up.
In equation (1) it gives the expression for determining E_EMF which for my application is what I care about, I think (see below for details on my application).
What confuses me is this: If my goal is to, as accurately as possible, determine the overall uncertainty in a system consisting of a DMM and a Switch module, do I use the "Differential thermal EMF" as found in the switch data-sheet, or do I need to try and estimate temperatures in the switch and use the equation?
*MY answer to my own question:
By carefully re-reading the example in the thermocouple section of the switch, I realized that they calculate 2 EMF's, one for the internal switch, calculated as 2.5uV (given in the spec sheet of the switch as the typical value) and one for the actual thermocouple. I say actual, because I think my initial confusion stems from the fact that the documenation talks about the relay/switch junctions as thermocouples in one section, and then talks about an external "probe" thermocouple in the next and I got them confused.
As such, if I can ensure low temperatures inside the switch at the location of the junctions (by adequate ventilation and powering down latching relays), I should be able to use 2.5uV as my EMF from the switch module, or to be conservative, <12uV max (from data sheet of 2527 again).
I guess now I have a hard time believeing the 2.5uV typical value listed.. They say the junctions in the relays are typically an iron-nickel alloy against a copper-alloy. Well, those combinations are not explicitly listed in the documenation table for Seebeck coefficients, but even a very small value, like 0.3uV/C adds up to 7.5uV at 25degC. I'm thinking maybe the table values in the NI documentation reffers to the Seebeck values at 25C?
Project Engineer
LabVIEW 2009
Run LabVIEW on WinXP and Vista system.
Used LabVIEW since May 2005
Certifications: CLD and CPI certified
Currently employed.

Seebeck EMV needs temperature gradients , in your relays you hopefully have low temperature gradients ... however in a switching contact you can have all kind diffusions and 'funny' effects, keeping them on same temperature is the best you can do.
Since you work with a multiplexer and with TCs, you need a good Cold junction ( for serious calibrations at 0°C ) and there is the good place for your short cut to measure the zero EMV. Another good test is loop the 'hot junction' back to the cold junction and observe the residual EMV. Touching (or heating/cooling) the TC loop gives another number for the uncertainty calculation: the inhomogeneous material of the TC itself..
A good source for TC knowledge:
Manual on the use of thermocouples in temperature measurement,
ASTM PCN: 28-012093-40,
ISBN 0-8031-1466-4
(Page1): 'Regardless
of how many facts are presented herein and regardless of the percentage
retained,
all will be for naught unless one simple important fact is
kept firmly in mind.
The thermocouple reports only what it "feels."
This may or may not the temperature of interest'
Message Edited by Henrik Volkers on 04-27-2009 09:36 AM
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'

Pxi-4071 shielding cable

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