Tee Rosette strain gage example with DAQmx

[sean_dowling]

I am a little confused with the Tee Rosette option in the "DAQmx Create Virtual Channel" (VI).  I am installing a number of accelerometers, single axis strain gages and a Tee Rosette (2 grids on the single gage, oriented 90 degs from each other).  They are all attached to a test article involved in an impact test for triggered, short-burst high-rate acquistion.  The way I have set up the program is to include all the sensors in a setup task, which is then included in a higher level routine which deals with arming the system and waiting for the impact trigger.  The file I have attached is the sensor/task setup vi.

The accelerometers and single-axis gages are straightforward, however, my confusion arises when trying to set up the Tee Rosette.  One of the options available in the "DAQmx Create Virtual Channel" VI is to identify "AI Rosette Strain Gage", and then further specify the rosette configuration (I select Tee Rosette).  Questions are:

1) How do I link two input channels to the different orientations of the same strain gage?

2) Is the "gage orientation" referring to the angular orientation of the binary gage to some arbitrary test article coordinate system (which you decide) or is the gage orientation asking what the angular orientation of grid 2 relative to grid 1 on a given tee rosette (I thought this was always 90 for a tee rosette).

Anyway, if someone has a chance, pleaase take a look at the file I attached and let me know if this is set up correctly?  And if not, some info on how to do it correctly.  Feel free to make any other related suggestions.  Thanks in advance.

[MCOTO]

Hello,

You define the different orientations with the Rosette Configuration terminal selecting the Cartesian X/Y respectively to each channel (in the same order). Please refer to the link below for more information about these properties.

http://zone.ni.com/reference/en-XX/help/370469AA-01/daqmxprop/attr2ffd/

You will find some examples about Strain Measurements from the NI Example Finder (Help >> Find Examples >> Hardware Input and Output >> DAQmx >> Analog Input).

[sean_dowling]

Thanks for the reply.  As I mentioned in my initial post, the single-axis gages are straightforward.  My questions were regarding options in the AI Rosette Strain Gage VI specifically.  The examples you suggested are all single-axis gage examples.  Going back to my questions, to clarify:

1) Outside of my own custom names on each gage of the rosette in their respective measurement VIs, how do I link the "Cartesian X" measurement of rosette 1 to the "Cartesian Y" of Rosette 1 (and not Rosette 2 for example)?  It seems as though there are numbering items available "Rosette Configuration" of the VI to achieve this but it is not clear to me on how to make this link (outside of traditional naming, which, in my opinion, removes the need for this option...i.e. someone spent the time to code it and it seems likely to be more than a pre-configured naming option).

2) Is the "gage orientation" referring to the angular orientation of the binary gage to some arbitrary test article coordinate system (which you decide) or is the gage orientation asking what the angular orientation of grid 2 relative to grid 1 on a given tee rosette (I thought this was always 90 for a tee rosette).

[sean_dowling]

Further to the above reply, when I run the VI with only one channel associated with the "AI Rosette Strain Gage" DAQmx virtual channel, I get the following error:

Error -201446 occurred at DAQmx Create Channel (AI-Strain-Rosette Strain Gage).vi:1
Possible Reason(s):
Each tee rosette requires two physical channels. Make sure the physical channel list contains two physical channels for each tee rosette.

This indicates to me that it requires 2 channels to be associated. However, when I "Create" a constant for the channels node of the VI, it only lets me select 1 channel?!  How do I associate both channels of the Rosette to the VI as it requests??

[javihn]

I do have the same problem with my DAQmx, but in my case I am using a Rectangular Rosette and the message it pops out is: Error -201447 occurred at DAQmx Create Channel (AI-Strain-Rosette Strain Gage).vi:1 The selected rosette requires three physical channels. Make sure the physical channel list contains three physical channels for each rosette.

How do I add and connect the other physical channels to the AI Rosette Strain Gage if this only allows a 1 physical channel connection.

Somebody help me, Please.!!

[RavensFan]

It would help if we saw your VI.

But if you are using a DAQmx channel constant, you can click on it and choose Browse.  You get a dialog box.  You can select multiple channels by using shift and/or control while clicking on the channels.  (Same functionality as if you were trying to select files in a Windows Explorer window.)  Once you hit okay, you can see how it structures the names in the constant or control.  Once you learn the pattern, you might be able  to edit the values yourself and edit or add channels.  (dev0/ai0:7) would be the kind of thing you'd see if you were picking channels 0 through 7 on Device #0.

[javihn]

Hi,

This is a program designed for Strain Gauge measurments using a Rectangular Rosette Gauge.

My problem is that I do not know how to add those physical channel to make this program work.

Thanks

[Cavarval]

Hello,

See my reply in your other post. 

Hope it helps,