9237 with full-bridge load cell: load cell_null_off_shuntcal.vi throws error 200077

Hi,
I'm trying to use the example
load_cell_null_off_shuntcal.vi with a full-bridge load cell (Honeywell
Model 31, unamplified). I am using LabView 8.6, cDAQ-9172 and NI9237. The
load cell is connected to pins 2,3,6 and 7.
The inputs for the VI front panel
are: internal excitation10V; mV/V 2.1492 (calibration sheet); max weight 10
lbs; bridge resistance 350 ohms (Honeywell specs); 9237 internal shunt
resistance 100 kohms; shunt location R4 (default setting). I have selected
"Do offset null" and "Do shunt cal".
This is the error I receive:
Error -200077 occurred at DAQmx
Perform Shunt Calibration (Bridge).vi:1 Possible reason(s):
Measurements: Requested value is not
a supported value for this property.
Property:
AI.Bridge.ShuntCal.GainAdjust
You Have Requested: -61.980405e3
Valid Values Begin with: 500.0e-3
Valid Values End with: 1.500000
If the "Do shunt cal"
green button is not selected, there is no error. I understand that the Gain
adjust value should be approx 1, whereas the one I get is much larger. The subVI DAQmx PerformShuntCalibration
(bridge).vi contains a "Call library function node" which I don't
know how to interrogate.
Has anyone else had experience
with this error? Do you have any advice on:
1)
How to "see" the calculations being
perfomed inside the "call library function node"?
2)
What the correct shunt element
location for a full bridge load cell is? (although changing this location does
not eliminate the error, I can't find this info).
3)
Anything I may be doing wrong with
my inputs to cause this error?
Thanks,
Claire.
Solved!
Go to Solution.

Hi Claire,
You have to physically connect the SC terminals to one arm of the bridge (normally R3). The terminal is not provided for connecting external resistors.
See example
C:\Program Files\National Instruments\LabVIEW 8.6\examples\DAQmx\Analog In\Measure Strain.llb\Cont Acq Strain Samples (with Calibration) - NI 9237.vi
"A VI inside a Class is worth hundreds in the bush"
യവന്‍ പുലിയാണു കേട്ടാ!!!

Similar Messages

9237 + full-bridge load cell: load cell_null_off_shuntcal.vi - error 200077

I'm trying to use
load_cell_null_off_shuntcal.vi with load cell (Honeywell Model 31,
unamplified). I am using LabView 8.6, cDAQ-9172 and NI9237. Inputs:
internal excitation10V; mV/V 2.1492 (calib. sheet); max weight 10 lbs; bridge
resistance 350 ohms (Honeywell specs); 9237 internal shunt resistance 100
kohms; shunt location R4 (default setting). Have selected "Do offset
null" and "Do shunt cal".
Error -200077 occurred at DAQmx
Perform Shunt Calibration
(Bridge).vi:1 Possible reason(s):
Measurements: Requested value is not
a supported value for
this property.
Property:
AI.Bridge.ShuntCal.GainAdjust
You Have Requested: -61.980405e3
Valid Values Begin with: 500.0e-3
Valid Values End with: 1.500000
If "Do shunt cal" green
button not selected, no error. Gain adjust should be approx 1. subVI
DAQmx PerformShuntCalibration (bridge).vi contains "Call library function
node" which is locked (?).
Any ideas?
What is the correct shunt element
location for a full bridge load cell? Changing this location does not eliminate
error.
Solved!
Go to Solution.

Hello CFJ,
The problem is most likely in your external connections of the NI 9237 and the load cell. As referenced in the NI 9237 Operating Instructions and Specifications, page 9, the SC+ and SC- pins should be connected across the resistor specified in the DAQmx Perform Shunt Calibration (Bridge).vi (in the case of a full bridge it would be R3).
Let me know if you are still having issues with your calibration.
Message Edited by Dan_K on 01-22-2009 04:31 PM
Regards,
Dan King

Generate PWM signal with 6602 utilizing load cell feedback

Hi Everyone,
I am new to LabVIEW so I apologize if this question is elementary but I really need some help with the coding. First of all, I need to generate 8 independent PWM signals to control 8 separate linear acuators using the NI 6602 board. I have each actuator wired to their own COUNTER OUT pins and ground on the SCB-68 that is connected to the 6602. The specs for the actuators state that it will take an input of "RC input range of 1.00 to 2.00msec pulse widths @ 55Hz. Bandwidth=.44to160Hz. Period from 6-23 msec". How can I code for these PWM signals given the specs from the manufacturer?
In the end I need to be able to not only control these actuators based upon duty cycle, but based upon the load each actuator is applying. Each actuator has a load cell in series measuring the tensile force through the load cell (the actuators will be pulling on strings). Each load cell is wired to a NI 9237 in a NI 9074 block that is connected via USB to the same computer. So first comes first, how can I code for the load cell output to be brought into the LabVIEW environment?
My last question is pulling this all together. How can I code so that I can input a specified load into LabVIEW and then based upon the value the load cell is reading, the duty cycle of the PWM will be adjusted until the the desired load is achieved?
Thanks in advance for any help! Also, I know that this is quite a complex questions so if you can even point me in the direction of resources that would be helpful, I would greatly appreciate that too!
Thanks,
Ryan

Hello Ryan,
Here's a tutorial on generating PWM with LabVIEW:
http://zone.ni.com/devzone/cda/tut/p/id/2991
How are the load cells outputting the data? Is it an analog signal? If so, you can read that in using an analog input task, and run that in parallel with the PWM task. Then you can modify the frequency and duty cycle inputs that you're giving you the DAQmx write inside the PWM code based on the analog input. By putting the DAQmx read and the DAQmx write in the same for loop, you can read from one and modify the other at the same time.
Here's a tutorial that shows a lot of useful information for using DAQmx within LabVIEW:
http://zone.ni.com/devzone/cda/tut/p/id/2835#toc6
If you're interested in getting better at LabVIEW in general, NI has some learning materials available here:
http://www.ni.com/academic/students/learnlabview/
Let me know if you have any further questions once you've gone through those first two tutorial links.
Colden

Load cell simulation with PXI system

Just curious if any of you have tried to do this...
I'm using LabView and my PXI chassis to test a board that interfaces with a load cell. The load cell is 2mV/V with a 3volt excitation voltage so full scale would be 6mV. I was hoping to do a sweep in increments of 1mV. So two signals S1 and S2, e.g. S1=2.000 S2=2.001, S1=2.000 S2=2.002, then S2=2.003 etc...
The only analog outputs I have are the two 12 bit outputs form the 6040E MIO card...not enough resolution.
I was thinking maybe I could buy some sort of accurate multiplying DAC and control it with the Digital lines from my PXI system. Anyway I was just curious if any of you guys and gals had done something similar...or maybe there is a low cost pxi card that I could use...but
I doubt it...my budget is limited right now.
Thanks and regards

Mashman,
Have you considered using an external reference to increase the resolution of the analog output channels on your 6040E? You could definitely get your code width below the 1 mV level that your application requires. Below are links to a couple of documents that discuss the use of external references:
Resolution of Analog Outputs
Outputting a Voltage Using an External Voltage Reference
Good luck with your application.
Spencer S.

Is it possible to tag a pdf with 'reject', so when it loads into Bridge, it will be pre-rejected?

Is it possible to tag a pdf with 'reject', so when it loads into Bridge, it will be pre-rejected and not view (so long as 'show reject files' is unchecked in Bridge)? - Please see screen shot.
We're wanting to have all pdf's initially set, so they don't view in Bridge, until the 'reject' tag is then removed.
Any help would be great! Thanks.

Well, not possible directly because the Acrobat interface doesn't allow changing Bridge's ratings and labels. But as Omke Oudeman showed over in the Bridge Scripting forum, they are stored in the XMP metadata, where "Reject" seems to be an xmp:Rating of -1. Thus you may be able to add this bit of metadata within Acrobat Pro by using the Append... [XMP template] command -- assuming you can come up with an XMP template, and can find the command buried in the interface (in Acrobat 9 it is behind the Additional Metadata button on the Properties/ Description tab, and then from there under Advanced). Another route might be via Javascript. Either way, before investing much time you should consider that most software won't see labels and ratings you add to the XMP metadata, and, as Omke mentions in that thread, their rendering seems somewhat fragile even in Bridge.
Another route might be adapting a metadata category already available in Acrobt's interface: Keywords, say, "Approved" and "NotApproved". (If you can't touch the Keywords, maybe you could re-purpose another of Acrobat's categories; and of course my suggestions are not related to Acrobat's stock stamps "Approved" and "Not Approved," a different kettle of fish). Keywords might suffice for you to filter views in Bridge, but if you really want Bridge to show files with "Reject" then they must carry that tag. If neither an XMP template nor an Acrobat Javascript serves, I imagine a Bridge script could apply "Reject" to files with the keyword NotApproved. Of course, for any PDFs whose status changes you'd need to adjust both the Reject (xmp:Rating -1) and the keyword; perhaps another script could un-Reject and change the keyword to Approved in one step.

I have a PC running Windows XP (yes an antique) with CS3 Photoshop and InDesign and lightroom 2 (yes all antiques). I have acquired a PC running Windows 7 with no programs. I also have a MacBook pro with full CS5 suite. The programs were already loaded w

I have a PC running Windows XP (yes an antique) with CS3 Photoshop and InDesign and lightroom 2 (yes all antiques). I have acquired a PC running Windows 7 with no programs. I also have a MacBook pro with full CS5 suite. The programs were already loaded with I got it as a gift. Question 1. If I find serial numbers used to download programs to the old PC, can those CS3 programs be put on the newer PC. Question 2. I really want to put CS5 suite on PC machines. Is that possible? Especially since my MacBook is showing some hard drive problems.

You should be able to get the CS3 programs installed and running on the new pc since CS3 is spec-ed for Windows 7 Service Pack 1. Downloading the programs does not require a serial number. You can find them here: Download CS3 products but you will need the serial number to activate the programs. You might be able to find that thru your Adobe account online.
You will not be able to install the CS5 Mac version on a PC and you won't be able to trade it to a PC version either due to it being an older version. Trades are allowed only for the latest version (CS6)

Modbus communication with a load cell

Hello..!
I'm a new user of LV and I try to communicate with a load cell by RS232 modbus.
After installed NI Modbus Library I created a master VI with labview 8.6 using these library, and I can obtain a communication with load cell , these value are added into 1 register U32Bit, and it's okay, if I press a load cell I can see the values go on.( from 0 to 65535) . Now I want to show on front panel the value in KG , as decimal point,, for a right interpretation of value for my customer, so I added a block array to unbundle than I convert a value with I32Bit ( -32768 to 32768 ) with an indicator, but I can't see any values..
I suppose I doing something of wrong ( conversion ), I read some KB, but I can't see a suitable solution..
Can someone give me a link or information to show me an example to convert this value..?
Thanks in advance for any helps..
Configuration of MAster VI:
Read holding register
Starting address 2012 ( query for obtain net value from the load cell)
quantity 1
Slave address: 1
RTU
9600
Com 3
parity none
Solved!
Go to Solution.

Hello Ravens,
I tried to use your good advices and finally I can communicate correctly with my trasducers showing on front panel the right value ( Kg). Has been a problem of conversion from output of register ( U16Bit as 0-65535 ) to I16bit ( -32765 to 32765).
Thanks very much for your help, and I hope to chat again for new challenge...
Have a nice WE
Julio
Attachments:
Comunicazione Modbus load cell.jpg ‏46 KB

Is it possible to condition a load cell signal with a 1520 SCXI and then use it as the primary analog feedback for a 735X motion control board?

My system
PXI 1052 chassis
PXI 8196 RT controller
Flexmotion 7356 motion controller
Flexmotion 7354 motion controller
6259 M series DAQ
1520 SCXI
1520 SCXI
1314 SCXI frount mounting terminal block
DSM strain gage load cells
Exlar SR Brushless PM motors
Kollmorgen servo star CD series 5 drives
My objective:
I want to measure the force on the load cells with the 1520 SCXI (i.e. excite the load cell then amplify and condition its output) then I want to use this analog (force) signal as the primary feedback for my motion control system (7356 and 7354 motion controller connected to my drives and motors).
The problem:
The motion controller boards (7356 and 7354) can be configured for force feedback control via analog feedback from a load cell. However the boards implicitly expect the load cell signal to be amplified and conditioned with and external signal conditioner rather then using an NI SCXI module. Currently I’m am reading the SCXI signals via the 6259 M seriers DAQ and consequentially have no way to route the signal into the 735X boards for force feedback control. I can use softmotion to control the motors but then I loose the fast PID update rates possible with the 735X boards.
The question:
Is it possible to condition a load cell signal with a 1520 SCXI and then use it as the primary analog feedback for a 735X motion control board?
Thanks
Patrick Aubin
Ph.D Candidate
University of Washington &
VA MedicalCenter of Excellence for
Limb Loss Prevention and Prosthetic Engineering

Hi GG,
Thank you for your feedback.
>create your own external circuitry to amplify the signal.>
True a few op-amps could amplify and filter the signal externally but the performance of such an amateur built system will never match the accuracy and functionality of the 1520 SCXI. That’s why we spent the $2500 for the professional version.
>One thing that you could do is to use a UMI with your motion controller and then wire your signal from your SCXI to the UMI.>
As I understand it the UMI is basically a break out connectivity interface for third party drives. After conditioning and amplifying the analog force signal with the SCXI module the analog signal isn’t available to wire into a UMI. To my knowledge the conditioned signal of the SCXI resides only in the PXI backplane (i.e. there is no physical access to the conditioned analog signal). Can you explain how the UMI could be help here.
Again thanks for your input GG.
Patrick

NI 9219 with load cell

Hello,
I am using the NI 9219 with a Futek Load Cell whose specifications are as follows:
Name
Min
Typ
Max
Unit
Channel: 1
Compensated Temperature
60
160
F
Excitation
1
20
Vdc
Hysteresis
-.25
.25
% of R.O.
Input Resistance
744
Ohms nom.
Insulation Resistance
500
Mohms @ 50 Vdc
Nonlinearity
-.25
.25
% of R.O.
Nonrepeatability
-.05
.05
% of R.O.
Operating Temperature
-60
200
F
Output Resistance
700
Ohms nom.
Safe Overload
150
% of R.O.
Temperature Shift Span
-.01
.01
% of Load/F
Temperature Shift Zero
-.01
.01
% of R.O./F
Zero Balance
-1
1
% of R.O.
Capacity
500
lbs
Rated Output
2
mV/V nom.
Calibration Excitation
10
Vdc
I am getting a signal from my load cell which is great, but I was wondering how you can adjust the signal output to have minimal interference from noise, vibrations, etc. and how to program the load cell that it can be calibrated to zero (0) before any data is aquired?
Any help is greatly appreciated!
Thanks,
Yatsco

Hello Yatsco,
Thank you for using NI forums. One thing you will probably want to look into is using the filtering VI's in LabVIEW. A low-pass filter can help to eliminate any high frequency noise from your measurement. Also, take a look at the Field Wiring and Noise Considerations article for some more information on eliminating noise. Lastly, this community example shows how you could calculate the DC offset and compensate for it before measuring your signal. Please let me know if you have any additional questions concerning this application.
Regards,

Load cell with labview 6

Hey guys,
I have to write load cell program with labview 6, but I have no idea how to do it.
If anyone knows, please give some hints.
Thank you

If you have little LabVIEW programming experience, the link below would be a good place to start:
http://www.ni.com/gettingstarted/labviewbasics/
I've also located a good example on ni.com/community that shows how to monitor a load cell in LabVIEW
https://decibel.ni.com/content/docs/DOC-2151
I hope this information is helpful.
-Nick-
Nick C | Staff LabVIEW Platform Product Support Engineer | National Instruments

DAC voltage capped when operating in torque mode with load cell feedback

Hi, i'm doing a tension control on a cable driven system using servo motor. I had connected a load cell as analogue feedback for cable tension into the labview programme suggested in http://www.ni.com/pdf/manuals/371242c.pdf (Figure 13-3. Torque Control Using Analog Feedback Using LabVIEW)
Problem 1: The response between desired tension and actual tension is good until about 80N, when the motor stops responding to higher torque changes. The voltage output in DAC is only 4-5V (max voltage output is suppose to be 10V) and the motor and amplifier had been verified to run up to 200N. What is limiting my DAC?
Settings:
Card: PCI-7350
Analogue input: 0-5V
Problem 2: I had implemented a low pass filter of 30Hz in MAX for the load cells. The effect is quite good for the low tension. However, as the tension increases, the noise increases proportionally too, causing vibrations and switching sounds to be heard at higher tension. Is there anyway to overcome this?
Please help. Thanks

I can't see anything special with your settings, so I currently don't have a clear understanding, why the output voltage is limited.
Could you please test the analog output? You could do this configuring the axis as an open loop stepper axis. This will allow you to set the analog output with Load DAC.
Does this allow you to output higher voltages?
Could you please do the test with and without signal connection to the analog output? Maybe the input impedance of your drive is too low and pulls down the board's output voltage.
I hope that helps,
Jochen

A/C three Phase motor control using 1/4 bridge Load Cell output and a USB 9172 Daq

NI Assistant,
I am tasked with setting up a Motion Control using two each OMEGA LC712-100K, -50K and -10K load cells to monitor the cable tension on six A/C motor driven winches. I also need to Monitor and calculate a Moment as well as the load slope for Load verses Time.
I have zero time to develop and I have searched your databases for existing Motor Controls to modify.
Should I use Case Structures and then place them in a while loop?
I setup a drawing in Word to visually define the task.
Signed,
Patrick Murphy
Attachments:
Layout for Testing Spars.docx ‏15 KB

Hi Patrick,
The reason why the Motion Control examples will not work for you is beacuse they are meant to be used with the NI Motion boards. Since you are using DAQ boards, the examples are probably not going to be able to help you too much. However, there is one example on the community that might be a place for you to start.
pmurphy wrote: Should I use Case Structures and then place them in a while loop?
What exactly do you mean by this? What do you want in the case structure or while loop?

Servohydraulic control with load cell feedback

Hello,
We are planning to build a tie rod fatigue test system with Labview and NI PCI-7344 4-Axis Motion Control Board. We have two linear servohydraulic actuators for applying linear force to tie rod and a servo motor for steering wheel movement. Tie rod must be vibrated by linear servo hydraulic actuators with constant force (+/- 50N , compression and tension direction) as 20 Hz while the steering turns (this is for road simulation) .
I think we can generate the 20 hz triangle waveform with 7344 motion control board for controlling servo hydraulic. But the main problem is to apply stable force with servo hydraulic actuators while steering wheel is turned by servo motor with constant frequency. There are two load cell as load link in the system so can we solve this problem with connect load cell to 7344 as feedback ?
Could you please share your opinions about hardware and software selection and application? What do you think about onboarb programming for this system?
I have attached two images regarding this systems which was build by some companies.
Best Regards
Steward

Steward,
I think you should be able to use the analog feedback feature of the 7344 to accomplish your task. Please refer to this link where you can find an attachment that explains the details of using analog feedback.
I don't think that you will need any onboard programming for the control task but depending on your security needs you might want to use it for emergency stop actions (e. g. when something goes wrong and the speed or the force become too high).
Please note that the 7344 does provide 12 bit ADCs for analog feedback. If the accurracy of these ADCs is not enough for you you should consider to use a 7356 instead which provides 16 bit ADCs.
Please read the document linked above. If you find that for some reason analog feedback is not the solution for your task we can talk about other options.
Best regards,
Jochen Klier
National Instruments Germany

DAC - Can I run more then one Exection Plans with full load option enabled?

Hello All,
I have configured for subject Area sales – Orders, Backlog and Invoices (OBIEE)
Now I want to run DAC to load the underline tables for subject Areas Financials – Revenue Analysis and Financials – GL Budget and Expenses, I have identified the relevant fact tables and built a Execution Plan in DAC.
DAC - In which mode should I run the execution plan?
With full load option enabled or disabled because already full load run is done for sales – Orders, Backlog and Invoices and this run should not disturb the existing data
If I run with full load option enabled do it overrides the existing data for other subject area
Please help me I am bit confused!
Regards,
SMA
Edited by: SMA on Aug 18, 2009 3:36 PM

No need of combining all the subject areas into one execution plan. Simply run the second ETL without checking the full load option. It will do the full load for the tables related to the newly added subject areas and incremental for the common tables between old and new subject areas.

Shaker control with output from load cell

Hi
I am using a (analog output) shaker to generate sinusoidal forces at different frequency and of different magnitude. I am also using a load cell (analog input) to sense these forces . The max force generated by shaker decreases as I increase the frequency of vibration. Whereas, the experiment requires the force to be constant when the frequency is changing. I plan to use the max force obtained from the load cell data, as the process parameter, to modify the amplitude of input wave which excites the shaker. I seek help in this regard. I am using PCI6221 and SCC68.
Thanks in advance.
RSD

Sorry, I have been extremely busy the last couple of days (months?). I still haven't had much time to ponder the problem, but one thought comes to mind, at what frequencies are you running this and what is the load cell, and its supporting electronics, frequency response. You mention that the amplitude decreases as the frequency increases, but that you increase the gain of the driver amplifier. It (the system) is most likely non-linear in its response, so how much you increase the gain will vary. The nonlinearity of the response is one of the reasons there is so much published about control systems, PID controllers, etc.
Putnam
Certified LabVIEW Developer
Senior Test Engineer
Currently using LV 6.1-LabVIEW 2012, RT8.5
LabVIEW Champion

9237 with full-bridge load cell: load cell_null_off_shuntcal.vi throws error 200077

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