Output gain adjustment factor from DAQmx Perform Shunt Calibration (strain).vi

Hi
We are using the DAQmx Perform Shunt Calibration (strain).vi to apply a gain adjustment to the output of our strain gauges. We would like to view the Gain Adjustment applied by the DAQmx Perform Shunt Calibration (strain).vi, and we have tried to do this using a property node.
I have attached screenshots of the property node we included before the DAQmx Perform Shunt Calibration (strain).vi (which seems to work fine), and the property node we have included after the DAQmx Perform Shunt Calibration (strain).vi (which doesn't output anything).
Could someone please advise of what I am doing wrong, or if ouputting the Gain Adjustment applied by the DAQmx Perform Shunt Calibration (strain).vi is even possible?
Cheers
Bart Scicchitano
(using his supervisors NI account with her permission)
Attachments:
ShuntCal_GainAdjustFactor_Before.PNG ‏29 KB
ShuntCal_GainAdjustFactor_After.PNG ‏45 KB

Hello, thank you for your response.
Sorry I wasn't clear. We get 0 from the property node when using multiple gauges in series. We have since found that the property node works when outputting the gain adjustment factor from only a single gauge, but we still cannot get it to work for multiple gauges in series.
I have posed the question in a more clear fashion (I hope) in the Labview forum (link below)
http://forums.ni.com/t5/LabVIEW/How-to-get-gain-adjust-from-multiple-strain-gauges/m-p/2304956/highl...
Thank you again for your response
Bart

Similar Messages

Shunt Calibration Failed

Hello! I'm pretty new to LabVIEW so I apoligize if I am confusing.
I'm trying to put together a VI that will take the strain measurements from four gauges, initially based off of the example provided through the "Strain - Continuous Input.vi". I'm using a cDAQ-9147 equiped with a NI 9237 and a NI 9944. Since our system won't be changing I wanted to set the Shunt resistor value and location as constants (100,000 ohm and R3, respectively). Unfortunately when I then try to run the VI with "Enable Shunt Cal" on I get an error::
"Error -201493 occurred at DAQmx Perform Shunt Calibration (Strain).vi:5630001
Possible reason(s):
Shunt calibration failed. The calculated gain adjust is out of range. Ensure that the shunt calibration terminals are connected properly and that the shunt resistance and shunt element location settings match how the hardware is wired.
Property: AI.Bridge.ShuntCal.ShuntCalAResistance
Corresponding Value: 100.0e3
Simulated Value with Shunt: 1.750000e-3
Measured Value with Shunt: 603.757856e-6
Property: AI.Bridge.ShuntCal.GainAdjust
Requested Value: 2.898513
Possible Values: 500.0e-3 to 1.500000
Channel Name: Axial 2
Task Name: _unnamedTask<A>"
I should note that the original example works on all gauges, so I know it's a mistake I've made somewhere. I've included the VI if that will help.
Thank you!
Attachments:
Strain_HELP.vi ‏98 KB

Hi Sunkistist,
This error can be caused by one of 3 things:
Your 9237 is so far out of calibration that the gain adjustment it would take to correct it is higher than the maximum supported by shunt calibration. Since the shipping example works, and your confident with the readings, we can assume this is not the case.
Improper physical connections. Again, we can rule this out for the same reasons as #1.
Improper configuration. Check to ensure the all the bridge resistance and strain gauge information is correct.
Here are some links you might find helpful:
Shunt Calibration with NI-DAQmx
Connecting Strain Gauges and Shunt Resistors to the NI 9237
NI 9945 or NI 9944 with an NI 9237 Connection Guide
Jeff Munn
Applications Engineer
National Instruments

Does the cRIO Scan Engine Support Offset and Shunt Calibration on the 9237 module

Thanks.

Sachsm,
The documentation for the Set Shunt Calibration (Scan Interface).vi should have been in the VI help but it looks like it didn't make it so I'll make sure it gets updated. I'll double check my understanding tomorrow morning but the documentation should be the following for the inputs of this VI:
slot - Specifies the chassis slot of the strain module (9237, 9235, 9236 ). Valid values are 1 through N, where N is the number of slots in the chassis.
channel - Specifies the channel to be affected. Valid values are 0-N where N is the channel for shunt calibration.
value - Turns Shunt calibration on or off. Valid values are 0 or 1 where a value of 1 will turn shunt calibration on for the given slot and channel.
Now, for your orginal question about offsets on the AI inputs, here are my addtional thoughts:
Unlike our SCXI products, the NI 9237 does not have an internal hardware nulling circuitry because its input range is sufficiently wide so that the inputs will not saturate even with a very large initial bridge offset. Since the 9237 does not have any hardware nulling circuitry, you have to perform offset nulling with software compenstation, and save the value to use later in the application as you mentioned. For example, when an offset null is performed in DAQmx, the entire offset is stored in the Initial Bridge Voltage property and is stored in software. You should see the same offset if you used the module from DAQmx, FPGA Interface, or in the Scan Interface. With that being said, I believe what your seeing is really just the resting measurement of the module and transducer together and you should be able to zero out your measurement by performing Software Compensation.
Regarding, Offset Calibration, I think its important to make clear exactly what it is providing as the name is a little misleading. The Offset Cal feature of the 9237 is really more like an Auto Zero used for eliminating offsets generated by an amplifier stage and doesn't provide the same behavior as offset nulling. In Auto Zero Mode, the 9237 shorts the input channel to ground and subtracts the obtained measurement from all subsequent samples. Performing an auto zero is a quick calibration technique that takes place at the beginning of a scan. A typical use of the Offset calibration feature would be to set it true at the begining of acquiring data and then leaving it on indefinitely.
Personally, I do not bother enabling offset cal in my FPGA applications because the measurement of the sensor at rest takes into account all sensor and module offsets.
And finally, if your looking for some information on how to perform shunt calibration, I like to refer to the example VI located here:
C:\Program Files\National Instruments\LabVIEW 8.6\examples\CompactRIO\Module Specific\NI 9235\NI 9235 Getting Started
As it has walks through the programming steps of setting up Shunt cal and applying the Gain Factors. Its written for LabVIEW FPGA but it should be easy to use with Scan Interface.
Hope that helps a little bit,
Let me know if you have questions and I'll help where I can or bug the right engineer.
Basset Hound

Gain error with shunt calibration

Hello,
I have a problem with shunt calibration of bridge based displacement transducers. The shunt calibration routine sets gain factors that give errors around 2% in the measured displacement. I have also found that the shunt calibration gain factors run out of bounds without a preceding offset null.
The hardware is a cDAQ-9188 with 9237 modules. The gauges have four wires, two input wires that I have connected to EX+ with jumper to RS+ and EX- with jumper to RS-/SC-, and two output wires that I have connected to AI+ with jumper to SC+ and AI-. LabVIEW is used with a VI shown in the attached figure.
Does anyone know why the shunt calibration behaves like that or what I do wrong?
/Emil
Attachments:
labview.png ‏19 KB

Hi Anton,
Setting the gain manually from a known displacement is not an option as some of the transducers are mounted so that they cannot be tested with gauge blocks.
Setting the DAQ Assistant Express VI or Create Channel VI to strain mode gives the same shunt factors as the general bridge mode.
I have done additional measurements to outrule any chance of coincidence with the sensing wires. With jumpers from EX+ to RS+ and from EX- to RS- on the first four of ten transducers the shunt factors are:
1.0046; 1.0246; 1.0347; 1.0246; 0.9649; 0.9811; 0.9600; 0.9720; 0.9591; 0.9793
with jumpers only on the first two transducers the shunt factors are:
1.0044; 1.0247; 0.9867; 0.9729; 0.9648; 0.9811; 0.9599; 0.9721; 0.9589; 0.9791
and finally for all transducers without jumpers the factors are:
0.9624; 0.9715; 0.9868; 0.9728; 0.9647; 0.9809; 0.9600; 0.9721; 0.9592; 0.9792
The conclusion is that the shunt factors are wrong but stable if the wiring is unchanged. Jumpers between EX and RS terminals effects the shunt factors. The shunt factors are between 0.04 and 0.06 larger with jumpers.
Should the RS terminals be connected for gauges without an extra sensing wire? Should there be a difference with and without the jumpers? Do you suggest anything special to look into regarding the EX wiring?
/Emil

Error Code -50150 from DAQmx Create Channel (AI-Voltage-Basic).vi

I have an executable, built from Labview 7.1 VI's. All it is doing is reading 6 voltages back from a 6008 USB-DAQ, and reporting the results back. Occasionally, it is throwing an Error -50150 from DAQmx Create Channel (AI-Voltage-Basic).vi. The full error message is:
Error Code: -50150
DAQmx Create Channel (AI-Voltage-Basic).vi<append>
Task Name: _unnamedTask<0>
Can anyone shed some light on this problem?
Cheers.

Hi fellas,
I have a really similar problem to the one Neilelph had, but I can´t see how to solve it from your answers. I attached a picture of my main .VI.
It´s basically a photodiode measurment system working as follows:
1. First the moving stages for the system get ready (X-Y moving stages for the Photodiode and Z stage for the Laser). That´s the CONFIG subVI in the left.
2. Then there is a For Loop, that repeats N times depending on the Initial Z, final Z and step values. So in this .VI the laser moving stage is the only one changing.
3. In each loop, the stages go to the X,Y,Z(t) posiition (MOV subVI), wait for the movement (WAIT subVI) and read the position. After that, the DAQmx acquistion part starts. I just sample the output DC voltage coming from the Photodiode (Dev1/ao1), 1000 samples in 1 second, and then I make an average of all of them with the Basic DC/rms block. So at the end I have 1 position of Z and one DC value. And it worked perfectly. At least for small number of iterations I have no problems.
The problem comes with small steps and a great number of iterations. For example last night I ran a measurement. 10000 iterations, the whole range of Z, and today i checked it. It worked fine until 5000 give or take, the half of the range. From that point, the DC ouput recorded in the .lvm file is just 0.00000. It´s the second time it happens, so I´m wondering what´s wrong because I´m affraid to make more long measurments and obtain the same results.
The error message I obtained is the same than in the thread title: -50150 DAQmx Create Channel (AI-Voltage-Basic).vi:6<append> Task Name: _unnamedTask<53BC>
Maybe it would be useful to mention that, sometimes, there is no error and I have some DC Output Voltage value, for random Z potitions, but since the first error message, that barely happens. The output is almost always 0.
Sorry for my writting skills in English. I hope you can understand my situation.
Thank you in advance.
Kind regards,
frilance.
Attachments:
Diagram.JPG ‏83 KB

Error 200380 occurred at DAQmx perform bridge offset nulling operation

I had a working VI that could balance a wheatstone half bridge and read and record measurements. My sensors are attached to a SCXI-1314 modle in a 1520 box in channel 0 (positioned as in the manual for half bridge) with the completion resistors in the appt places in ch7. It used 'custom voltage with excitation'.
Wanted to improve this VI so that it would also do a shunt calibration. I therefore connected the shunt resistor in the board over my active sensor as in the manual. I tried then to create a virtual channel for it - but it wouldn't work. So I gave up on that idea and tried to put things back how they were - deleted the virtual channel, and removed the connections to the shunt resistor. Except now none of my previously working VIs will work. I have built a new VI, and that can find a signal but not balance the bridge. I get:
error 200380 occurred at DAQmx perform bridge offset nulling operation.
I have checked the hardware again, and it's all wired correctly - it seems like the VI can see the channel but doesn't know what to do with it. Have running the VIs with and without a custom voltage with excitation channel created but nothing works.
Help!

Hi LucyWH
Have you tried re identifying the chassis in Measurement and
automation explorer?
Have you changed the jumpers at all as when rewiring this is easily
overlooked?
I have found some links that you may find useful:
Error -200380 When
Calibrating SCXI-1520 in NI-DAQmx
http://digital.ni.com/public.nsf/allkb/6E94108C9611910186256D43007C2584?OpenDocument
Common NI-DAQmx Error
Codes and Solutions: Codes -200300 to -200999
http://digital.ni.com/public.nsf/allkb/8A0E097385A4269586256DBA0054E668?OpenDocument
Regards
Robert
National Instruments UK & Ireland

Best way to mix multiple camera angles from multiple performances?

There has to be a slick way to do this, but I can't seem to figure it out. I'm hoping someone can offer their advice on the best way to approach this project. (I'm using Premiere Pro CS4)
I have footage from 2 performances of a high school play that I want to mix together, with 2 cameras used each night:
Cam1: Friday Right
Cam2: Friday Center
Cam3: Saturday Wide Left
Cam4: Saturday Wide Right
I only had 2 cameras, but I wanted to capture 4 different angles that I could later mix and match. The problem is that, as live performances go, you can't count on exact timing from night to night. It's really simple to do multi-camera editing for one night with the Multicamera Monitor (painfully simple), which works great for the 2 angles that were filmed on the same performance, but if I try to do it with footage from different nights, it only takes about a minute for actions onstage to be so far off between the two nights that I can't switch between cameras with reasonable accuracy.
Since I will be going back and forth many times among 4 clips, the ideal solution that I have come up with (but I don't think Premiere can do) is to have the ability to set markers or keyframes at certain locations that basically say "switch to MM:SS on camera X now" without actually trimming clips and overlaying them into a single video track. So basically determining which camera is "Live". This would let me do rolling edits without having to create a new clip every time I want to switch to that camera angle.
I may be missing something very simple or over-analyzing something that really won't be that bad, but I'm having a hard time wrapping my mind around the best way to approach cutting back and forth among the same 4 unsynchronized camera angles numerous times. If nayone has a suggestion I'd love to hear it.
Thanks,
-keen

Time - being in sync...
Most performances like that shot ( for like a music video ) are done to recorded music ( lip sync and play to recorded music ) ..so timing stays the same to the music... dont know what kind of performance you shot but this gives you an idea how tough it is to keep timing for music performances.
---------you wrote -----
Since I will be going back and forth many times among 4 clips, the ideal solution that I have come up with (but I don't think Premiere can do) is to have the ability to set markers or keyframes at certain locations that basically say "switch to MM:SS on camera X now" without actually trimming clips and overlaying them into a single video track. So basically determining which camera is "Live". This would let me do rolling edits without having to create a new clip every time I want to switch to that camera angle.
If you can't just use one night as suggested earlier by Jim and Stan....I would say bite the bullet and just do what you dont want to do...
make subclips ( trim clips or whatever ) and forget about rolling edits...
You might want to consider putting stuff in 4 sequences... day 1, day 2, day 3, day 4...
make a 5th sequence called "rough cut " or something...
each time you take a "clip" from one of the 4 sequences move that clip up one video channel ( and copy / paste to your 5th sequence )..which then gives you a visual quick guide what you have USED from the sequences...so you dont waste time scrubbing through stuff you already put into sequence 5....
You may be able to choose just ONE sound track from one night and just use THAT...and pick shots that FIT those moments in time OK from all 4 sequences....you can play with duration / time of a small clip ( as it is unlinked to the sound in this scenario ) to make it FIT better...but that would be very subtle changes...
ps...I keep forgetting...some people use the camera to record sound instead of a sound mixer, recorder, etc...so if thats your case what I suggested at bottom of mssg probably would not work...using duration / time...unless its REALLY minor adjustment...hmmmm, maybe export just the sound from a single performance and try using that as your ONE sound file for the performance...I really dont know what you would do if you recorded sound with the cameras...as I would never do that I dont know what to suggest if thats the case...

Audio Gain Adjustment for LOUD sounds sources?

Any developers know if a hardware adjustment like an audio level gain control is possible within a third party application. My canon digital camera allows me to manually attenuate loud sound sources with the assistance of a peak meter to prevent distortion from loud sound sources such as those in a live concert setting.
It's sad to see all these youtube video clips from live concerts with totally blown out audio which could have been prevented by a simple mic gain adjustment.

OK, I might have found a workaround. If you are indeed talking about mono audio mapped to stereo, there's a fairly simple solution: instead of using Audio Gain on a clip in a sequence, simply use it a on clip in the bin/Project Panel instead. To do this, just select the clips you want to use Audio Gain on, and then go to Clip > Audio Options > Audio Gain (CS5.5 has added this to the right-click menu). Even when mapped to stereo, there is no crash--at least, not in my testing. It seems to be OK even when the clips are already used in a sequence; note that it won't affect clips already in the sequence, though.
Does that work for you? Just did a quick test here...

Upgrade to CS5 from CS4 Performance issues

This was originally posted in the Creative Suites section. Bob Levine suggested I try a specific program forum to get better attention. It has been a present performance problem for me with Premier Pro and Photoshop so I shall try here.
I have been using CS4 for several months on a new i7 quad 64bit PC with 4 x 1TB HDs and 12GB RAM. When I use Photoshop or P.Pro, the performance is fast for several operations but slows down as I progress to a snail pace. At times, I have rebooted the PC to get up to speed again. I do not know if this is a problem with the CS4 32 bit program working on a 64 bit machine, even with Photoshop. Perhaps I am clicking too fast. If I install the source file on a separate drive to the C drive and send the output file to a third drive, performance improves as expected. Perhaps timing within/between drives and the 32 bit program may be a problem on a 64 bit PC. I have ordered an upgrade to CS5 hoping that a 64 bit program will provide better performance on the 64 bit PC. Naturally the PC performance is expected to be faster, but will the performance that slows down to a snail pace improve?

Thank you all for your information.
I am beginning to imagine that because of the increased speed in dealing with data, an i7 quad 64 bit PC has a challenging time to switch and route the stream of data to the various processing and temporary/permanent storage locations. It could be that dealing with 32 bit data for the demands of video editing compounds the problem. I may have one or several slower components in the new PC. In anycase, I am hoping that dealing directly with 64 bits will improve the performance. If this does not and without further suggestions from the forum, I will have the performance of the PC components thoroughly tested for compliance to the required speed specifications.

Extract single channel from DAQmx Task

Hello,
I have created a DAQmx output task, which contains two channels. Is it possible to extract individual virtual channels from the task to be processed by two parallel processes? I have tried bringing out the Channels Property using a Task Property Node, but I then get the error that the channel is not part of an active task (see attached snippet)
Could anyone advise on a better approach, or how to acheive this functionality - if it is possible?
Regards
Dave
Solved!
Go to Solution.
Attachments:
split out channels from DAQmx task.png ‏34 KB

Sorry, that VI does not make much sense. You have to use a single DAQmx Write for both channels and for 1 Sample mode, you simply have to build an array of the signals as shown below.
Attachments:
two channel write.png ‏12 KB

Restarting Task After Performing Shunt Calibration

Hi,
I wonder if anyone can help with a problem that I am having with LabVIEW 8.5. I am using LabVIEW to measure strain gauges via SCXI 1520 signal conditioning units.
To perform a shunt calibration of the gauges I use the National Instruments example code. The problem seems to occur after the 'CalculateGainAdjust.vi' has been called. The DAQ task is passed to the calibration code, 'CalculateGainAdjust.vi' does the following:
*passes the clock configuration to the end of the VI so the original state can be restored.
*enables shunt calibration
*creates a new clock
*starts task
*reads 1000 samples
*stops task
*disables shunt calibration
*restores task state
This code executes without causing an error. If the main DAQ task is stopped and then a calibration performed the task will not restart with its original configuration and times out with the following error:
Error -200284
DAQmx Read (Analog 1D Wfm NChan NSamp).vi:11<append>
Property: RelativeTo
Corresponding Value: Current Read Position
Property: Offset
Corresponding Value: 
If a calibration is performed before the DAQ task is started then the DAQ task starts ok after calibration. It is only if the task is run then stopped to perform a calibration that the problem occurs.
Is it necessary to take into account the 1000 samples read during the calibration process? I wonder if the main DAQmx Read VI is waiting for the 1000 samples that have been already read ? Strangely enough I don't think this was an issue when the code was run on LabVIEW 8.2
Any suggestions would be appriciated
Kind Regards
Ian

Hello Ian,
Thank you for the link pointing to the downloaded examples that you have been using. More importantly, I am also glad to see that you are able to use the examples and that you found an order of operation that does not cause any error codes. You are, however, interested in continuing searching to find what causes the error in the latter case of operation, which is what I will be helping with.
Just to be sure, I have a Knowledgebase Article linked below to help avoid the error, -200284.
http://digital.ni.com/public.nsf/allkb/FEF778AD990D5BD886256DD700770103?OpenDocument
As we said, the error can occur in the latter case because something is not being setup correctly with the DAQmx task, or because the Calibration procedure is making use of the the hardware resource, and not releasing it for the DAQmx task. I will have to do more research, and reply back confirming the cause.
The examples you are using seem to be the most current, although I will take the time to compare them with those that ship with LabVIEW 8.5, which you currently have. The examples have been available since the release of the modules. As the modules have not changed, it appears that examples are at their optimum level.
Regards,
George T.
Applications Engineering Specialist
National Instruments UK and Ireland

Expected Shunt Calibration Factors

I am trying to shunt calibrate (using a SCC-SG11) a rectangular rosette strain gage wired to an SCC-SG01 module. I'm using an SC-2345 hooked up to a laptop with a DAQCard-6036E. I am reading in an analog voltage with the SG11 engaged and subtracting the value w/o it engaged. The expected value of Vexpected=(R3*Vex*(Rshunt+R4))/(R4+Rshunt+R3*(Rshunt+R4)) is then divided by this difference to obtain the correction factor. For the Vexpected, R3=R4 correct? I am getting a correction factor value of less than 1 (~.97), which to me doesn't make sense, as the shunt calibration is supposed to correct for the wire resistance. Am I understanding this correctly that the correction factor should be >1?
Thank you in advance for your assistance
Solved!
Go to Solution.

Hi William,
If we look at what's going on internally in the SCC-SG11 by looking at pg 17-18 in the manual, it shows a diagram and a sample equation. Set all values to 120 to calculate your expected measurement and then vary it from 119 to 121 and divide by the expected value. If the resistance is higher than 120, you will get a lower measured voltage and a ratio >1. If the resistance is lower than 120, you will get a higher measured voltage and a ratio of <1.
Jake H | Applications Engineer | National Instruments

Need some hints for evaluating data from Central Performance History

Hi Experts,
I am pretty new to all the BI-stuff and hopefully someone can provide some hints. I got the requirement to read data (CPU usage/peaks) from central performance history of "system a" into "bi system" to generate overviews/charts/etc
Now I guess there might be a standard report/info cubes and stuff which will help to solve this.
I would really appreciate if someone could throw me a few keywords about this topic.
Thanks in advance!

Hi David,
Thanks, I hadn't looked at the note.
Section 2 - history of all connected systems showed me what to do to collect the data. I had seen that in the setup but not understood the implications of it fully. The note explained it much clearly than the SAP help.
Thanks again,
Gareth

[Photoshop CC 2014] Click&hold-move-release doesn't work when adding adjustment layer from the layer panel

When selecting a menu item I used to click the left mouse button and hold it down, move the pointer to the desired menu item and release the mouse button. Everything works fine in the mine menu, but there's a problem when adding new adjustment layer from the layer panel: when I release the button nothing happens, I have to press the button again. In previous PS version it worked fine. How can I fix this?

I don't think that is user fixable, meaning you'll have to wait till adobe fixes it with an update.
Photoshop cc 2014
windows does not work
mac does work
Did you already post over here:
[Photoshop CC 2014] Click&hold-move-release doesn't work when adding adjustment layer from the layer panel

I am trying to output a PDF gallery from CS6 bridge in 10.8.5 on a Mac.

I am trying to output a PDF gallery from CS6 bridge in 10.8.5 on a Mac. No options are available from the pull-down Output arrow.

Hello,
Although not as simple as it should be you can use a program like "Grab" to take a screenshot of the frame in the preview window in iMovie.
http://support.apple.com/en-us/HT201361
Hope This Helps,
Ryan (BURNINGJUNK)

Output gain adjustment factor from DAQmx Perform Shunt Calibration (strain).vi

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