CRIO NI 9237 calibration

Dear,
I have a torque to measure.
I would like more documentation on the calibration.
How to used the calibration of the NI 9237? (The LSB weight and the offset)
When I connect the calibration value in the VI "Binary to nominal.vi". But the result is like nul (1.10e-6).
Regards
Massif

Massif,
If you are using LV 8.5.1 you can install NI RIO 2.4 and get calibrated values right our of you FPGA read IO node in terms of Volts/Volt
See:
http://digital.ni.com/public.nsf/allkb/C18C172029D187CA8625741600664D89
If your using the calibrated values, then you no longer need to use the LSB and Offset values. (much nicer)
SteveA
CLD
FPGA/RT/PDA/TP/DSC

Similar Messages

Ni 9237 calibration -200077

I'm trying to calibrate NI 9237 + NI 9945 quarter bridge strain gage in ni max.
I get Error -200077 occurred at strain gage calibration.
Possible reasons:
Requested value is not a supported value for his property,
Property AI.Min
Requested value -1.0e-3
Valid values begin wih 18.8988984e-6
Valid values end with 103.843984e-3
Channel name: strain
I tried everything, different strain gages, different 9945's different 9237's, different cables, different computers. everything.
I changed every setting I could find in ni max.
I searched forums and inernet and what is there is not helping.
Any ideas? Please? I'm so desperate.
Solved!
Go to Solution.

I just got the same error message over and over.
What went down: When I set my min limit within the highest and lowest allowable values specified in the error dialog window, and then tried again, I got the same error all over again, but the highest and lowest allowable values shown in the window had changed to completely different numbers. This happened several times. No matter what I set my limits to, the max min allowable values would always change, so it would error out every time regardless of what I entered. Sometimes it would complain about the shunt calibration gain factor, that it couldn't set it to either "+inf" or "-inf". Looking closely at the calibration window, I noticed that NI MAX was reading the same strain value, both with, and without, the shunt resistor connected. When the calibraion subtracted Y2 - Y1, it got zero, and the inverse of zero is infinty. That's when I knew for sure it was something in my wiring and started looking into it more deeply.
Cause: Short in the lead wires running to the strain gage. When the specimen was assembled and bolted onto the fixture, the wires were obscured so that noone could see them, and they were crushed between two metal components.
Solution: Check for shorts or other issues in the strain gage wiring itself. I imagine if the strain gage circuit is open, then we would probably see the same error from NI MAX in that case as well.
Recommendation: I would request NI to add some more helpful information in the error dialog box, to suggest to the user to check wiring, etc.

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

Where can I find the CRIO-9102 Calibration and ADC to Voltage Conversion VIs ?

I am working through the "Developing High Speed Continuous Buffered Data Acquistion Applications with CompactRIO" tutorial located at http://zone.ni.com/devzone/cda/tut/p/is/3268 I am using a CRIO-9201 analog input module instead of the cRIO-9215 shown in the tutorial.
I would greatly appreciate help with the following:
Where can I find the cRIO-9102 calibration and ADC to Voltage conversion VIs?
Thanks

Thank you for correcting the link to the tutorial. For the sake of clarification here are my questions. I am fairly new to LabVIEW and very new to the cRIO platform:
1. Are the calibration VIs for specific modules available as part of LabVIEW or do I have to create my own using the property nodes for the module.
As I worked through the tutorial I modified the calibration VI for the cRIO-9215 as necessary so that it would work with the cRIO-9201 module that I am using.
2. I am assuming that the "Convert to Voltage (cRIO-9125).vi" shown in the tutorial will work correctly with the cRIO-9201 since I am passing cRIO-9201 calibration data to it. Is this correct?
Thanks
Thanks

Selecting bridge type for 9237 module on cRIO

How do you select 1/2 or Full bridge completion and Shunt settings for 9237 Bridge module on cRIO? The getting started example only seems to set the data rate?. The FPGA Property Node only has Data Rate, Excitation, and ID params available as choices? Am using 8.2.1. Other discussion threads talk about configuring with MAX but for cRIO/8.2.1 MAX doesn't show modules, just the remote system top level.
Thanks,
Bruce

Hi Bruce,
The Half vs Full Bridge as well as the Excitation Voltage settings live in the properties page for the NI 9237 module in the LV Project (right-click module item>>Properties). See attached image.
JMota
Attachments:
9237 properties page.JPG ‏36 KB

NI 9237 External Excitation - VeriStand 2013 SP1

The recommended excitation voltage for my pressure transducers is + 10 VDC. I prefer to use external excitation as per the NI 9237 manual, total power for the module is limited to 150 mW, which in my case is "Four 350 ohm full bridges at 3.3 V". (I will be using (4) full bridge 350 ohm pressure transducers). I am using Scan Engine for EtherCat and have the NI 9237 in a NI 9144 Chassis connected to a cRIO-9081. For troubleshooting, I have two transducers on a pressure calibrator and another RJ50 connection to a NI 9949 breakout. If I select "External Excitation" and have my 10 V power supply connected to the lower EX+, EX- connector, I get an invalid value for my pressure transducer. This is after scaling the value in calibration. The Raw Value is also incorrect. If I leave it set to "External Excitation" but pull the EX+, EX- connector, the EX+, EX- voltage (pins 6 & 7) will go to 4.735 V and I will get a CORRECT pressure reading. If I select Internal Excitation of 3.3V, I will get a correct pressure reading, but I am a little concerned about resolution as the recommended excitation is + 10 VDC for the pressure transducers. My question is: why am I unable to use the external excitation? I have another application with a PXI and EtherCAT chassis and it works OK. I've also tried placing a NI 9237 module in the cRIO-9081 chassis and get the same invalid value that I describe above.
Solved!
Go to Solution.

Do you have the latest version of the Scan Engine and EtherCAT custom device? On the community page for this custom device, the latest bug fix listed specifically refers to this module. Also there is a specific forum for this custom device that it may be a good idea to post on as well if you have not already posted there about this problem.
Miles G.
National Instruments
Applications Engineer

Null offset from calibration not being applied to output

I am measuring some load cells using a I 9237. I am setting the null offset using Device > Bridge Calibration in the DAQ Assistant. I measure the offet and hit calibrate. It says "Calibration successful" and I hit finish, but the offset value is not applied to the data.
How do I get this to work?

Hello IamRubber,
How can you see the calibration not being applied? Are you running the same DAQ Assistant to see the offset? If possible, please attach a screenshot from before/after running bridge calibration.
Patrick W.
Applications Engineer
National Instruments

NI 9214 FPGA I/O items missing (cRIO-9030 / NI 9144 combo)

I have a new cRIO-9030 and NI 9144 EtherCAT expansion chassis which I have configured and added to an existing LabVIEW project containing a cRIO-9012. When I searched for existing targets and devices, the modules were correctly detected (NI 9237, NI 9263 and NI 9265 on the cRIO-9030, and NI 9214 and NI 9477 on the NI 9144 chassis); however, the I/O items listed for the NI 9214 module show only the 16 thermocouple channels (TC0 through TC15). The four additional channels are not shown (Autozero and CJC0 through CJC2), although they did when the module was previously configured for the cRIO-9012. Is this a known / compatibility issue with the NI 9144? or is there a configuration option I am missing? Does the terminal block need to be in place on the module for these I/O items to appear?
Solved!
Go to Solution.

Hey CFER,
You are correct only the thermocouple channels are availble through the scan engine. The availabe channels for each module are documented in the compactRIO help. This should be the same for all chassis. Can you double check the 9012 was setup in FPGA mode? Its easy to overlook sometimes.
Kyle Hartley
RIO Product Support Engineer
National Instruments

9236 enable shunt cal property crashes crio OS with scan engine

I would like to inform users of the 9236 Quarter Bridge Strain Gauge Module of a bug. The Real-Time team is aware of this issue and I have been working with an app engineer on it for about a week and he has confirmed my findings. He says the problem is most likely a driver issue or scan engine issue and they are investigating it.
There is a bug that completely crashes the cRIO operating system with the 9236 module. Currently when a cRIO device is loaded with LV2009 SP1 or LV2010 and using scan engine interface, attempting to write the "shunt cal enable" property of a 9236 module completely crashes the VxWorks OS. If you try to access the property again, the crio crashes and enters an error state where the crio has rebooted twice without being told to. The LED indicator blinks four times to indicate this.
I have tested this with a few different hardware combinations with both the crio-9014 and crio-9012 controllers, combined with either the 8-channel 9104 back plane or the 4-channel 9102 back plane with the same results. The app engineer was able to duplicate this issue as well.
To duplicate the bug:
Load a crio device with 2009 SP1 or LV2010 and configure the device for scan engine. Locate the 9236 module in the project explorer and drag and drop it into a VI to create the IO variable. Right click the output terminal of the IO Variable and go to create > property > enable shunt calibration on a channel. Once the property is dropped, right click on it and do change to write so that you can write a boolean to the variable. It doesn't matter if you write a true or false to the property, the results are the same. Hit run, watch it crash. When it reboots, hit run again. The crio is now in a state that can only be recovered by physically resetting the device.
I love the crio stuff and I use it every day because it is very reliable and robust. This kind of thing is rare, which is why I am reporting it to the community as well as NI as it is a pretty big bug that took me a while to narrow down.
[will work for kudos]

rex1030,
Shunt calibration can be accessed using a property node. The operation will be the same, you still need to acquire two sets of data and compute the scalar.
You can obtain the necessary reference by dragging the module to the block diagram from the project. Please see http://zone.ni.com/devzone/cda/tut/p/id/9351 for more information on programmatic configuration.
Let me know if you have any other questions.
Sebastian

Binary to Voltage Conversion of encoder data on cRio 9073 using FPGA

I am using FPGA with a cRio 9073 to acquire torque and absolute quadrature encoder values. It says in the FPGA instructions that the documentation for the 9073 should include the binary to voltage conversion, but when I looked at the documentation, it wasn't there. Where can I find the conversion value or function to convert binary encoder data back to voltage? The encoder is hooked up to an analog converter and is acquired with a 9215 AI (+-10V differential). Thanks

There are individual formulas for one or a group of modules.
LabView examples path:
LabVIEW 2010\examples\CompactRIO\Basic IO\Analog Raw Host Calibration\AI Raw Host Calibration
LabView help topic
Converting and Calibrating CompactRIO Analog Input Values (FPGA
Interface)
Best regards
Christian

Can I detect if a module is present in CRIO FPGA?

I have a cRIO-9073 controller chassis with 8 NI 9237 modules. I plan to use FPGA reads - not the scan engine. Can I detect whether a module is present or not within my FPGA VI? If not, is there a way to do this within the RT Host VI? (This is my first cRIO project so I'm still a bit green). I can foresee my client needing to replace a module sometime in the future and still needing to operate the system with the remaining modules - so the system must be robust and adaptible to fault conditions.
- Thanks in advance
- Tore
Solved!
Go to Solution.

I switched to the Find Hardware VI and it doesn't error, but what I need is network devices. I have expansion chassis on the network that I need to confirm are connected. The Find Hardware VI only lists off local devices. I asked about the error over at this topic here:
https://forums.ni.com/t5/LabVIEW/LV-RT-System-Config-Find-Systems-vi-Error-quot-2147220620-quot/m-p/...
Thanks,
James
LabVIEW Professional 2014

NI 9237

Please help us with to setup NI 9237 and NI 9411 with NI cDAQ-9174 to measure the load, torque and angle at the same time. We are using RJ 50 for the connection between load and torque sensors to NI 9237.
For the Load cell, we wired positive and negaitve signals and exicitation pins. it is not reading properly....
Questions:
1. Exitation Voltage for the load call is 10V, do we need an external supply?
2. Do we have to attach the Shunt Calibration pins?
3. attaching the specification sheet for Load cell and torque sensors. Please explain.
Attachments:
sesnors.pdf ‏185 KB

Hi Kwindsor,
1. The NI 9237 can supply up to 10 V of excitation internally, so you shouldn't need an external supply.
2. You shouldn't need to connect the shunt callibration
Synchronize 9401 and 9237 Measurements will give you a good idea how to synchronize these measurements. The example is use a count edges task, but you can change this to an angular encoder task for your application. Can you get any measurements on your 9237 at all? This KnowledgeBase article will tell you how to configure this load cell measurement in Measurement and Automation Explorer to test the readings from your load cell.
Regards,
Jim Schwartz

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!!!

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

Strain measurement using 9237 and cDAQ 9172

I am trying to measure strain using a 9237 and cDAQ 9172.
The strain gage is connected to 9945 (Red wire to EX+, White to IN+ and Black to QTR terminal also tried connected the white and black to IN+ terminal).
The 9945 is connected to 9237 quarter bridge strain measurement module on a cDAQ 9172. I have two 9237 on the cDAQ 9172.
The device passes the test in MAX.
The problem is I cannot read the strain value.
Can anyone help me please?
Attachments:
Strain measure.vi ‏19 KB

Hi jujare,
In the VI you attached, you don't have the bridge configuration set up. The default is full bridge I, so if you have a quarter or half bridge wired up, that is one reason you could be getting bad data. I'd suggest you take a look at "Cont Acq Strain Samples(With Calibration)-NI 9237.VI" in the Example Finder. It shows the configuration for bridge type and has some handy wiring diagrams. You could also add controls to your vi to set the bridge configuration if you'd prefer.
If your strain gauge only has three wires, it's probably a half or quarter bridge. A full bridge needs at least four wires.
I hope this helps!
Regards,

CRIO NI 9237 calibration

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