DAQ Assistant -- Excitation Source

[bgg]

The DAQ board I am using is a SC-2043-SG.  I am trying to use the DAQ assistant to create a VI to measure strain from a strain gage, but every time I test the input, it gives me this error:

Error -200161 occurred at DAQ Assistant

Possible Reason(s):

Device to which the sensor is attached does not have an available internal excitation source.

Select another device with an available internal excitation source or supply external excitation.

Channel Name: Strain
Device: Dev1

This error was received when using an INTERNAL excitation source the board.  I have the mx drivers installed, so I know that is not the problem.  I the following at this site:

SC-2042RTD and SC-2043SG:
The SC-2042RTD and SC-2043SG can both be used with NI-DAQmx. If you are using an RTD or Strain Gauge Task or Channel you must choose external excitation and set it to the values provided by these accessories. Also, the SC-2043SG provides a gain of 10 to the strain gauge signal that must be taken into account.

So, I again tried to use the DAQ assistant, but changed the excitation source to external and a magnitude of 2.52V (that of the board).  When this is done, there is no error received upon testing, but it does not give appropriate readings.  Instead, it gives a straight line, and is unresponsive to changes in the applied load (the measurement was set to continuous). 

I cannot figure out what I need to do in order to get this working.  Any help would be greatly appreciated.

[bgg]

***bump***

[RavensFan]

What is the voltage level of the straight line?  Can you post an image of the front panel graph that shows the data?

What is your external excitation source?  What DAQ card are you using?  I am not sure what you mean by "but changed the excitation source to external and a magnitude of 2.52V (that of the board)"  Is the 2.52 V an external excitation or coming from the DAQ board the SC-2043-G is attached to?

I found a few links that may be of interest.  I searched ni.com for sc-2043-sg

The manual in case you don't have a copy  http://www.ni.com/pdf/manuals/371201a.pdf

And this one  Why Doesn't My SC-2043-SG Output an Excitation Voltage?

One about no excitation from DAQ Card http://digital.ni.com/public.nsf/allkb/FBC7EC7B8D1CDF9186256D89007A0BB5

This second link is kind of interesting in that it seems to contradict the quote from the link you provided.  It says:

 "If no DAQ board is connected to the SC-2043-SG, then the excitation voltage will not be provided properly. To correct this, short the following three pins together, and then tie them to your computer's ground (or to your external device's ground): "

This implies to me that if the SC-2043-SG is connected to a DAQ board (as I imagine it would be to acquire any readings) the the excitation would be provided properly.

Hopefully, somewhere in one of these links is a piece of information that gives you insight into what's going on.

[bgg]

Thanks for your reply and for the links. The third link applies to my case, I am actually using the SC-2043-SG with a DAQ board 6024E. The page you sent me says that I should not be using the cable 184670-02, rather I should use the cable 184670-01. I checked my cable and it is a 184749C-02. However, I should also add that the whole system, 6024E + SC-2043-SG, is already working with "traditional" DAQ drivers. I have a functional VI that uses the "AI read" function to read the voltages, converts them, and correctly displays the strains. So I am confident that everything is working, and the cable seems fine too.

What I am trying to do now is to migrate from the traditional DAQ driver to the DAQ-mx drivers, so that I can have one VI that can be used with both my SC-2043-SG+6024E system and with my new strain gage system, cDAQ-9172+9219, which only supports DAQ-mx. My first step was to write a simple VI that uses DAQ-mx to read strains from my older system.

Regarding the excitation voltages, I am only using the internal excitation provided by the 6024E to the SC-2043-SG. I don't plan to use any external sources. I had only switched the setting in the driver from "internal" to "external", to see if that would solve the problem, but I think it should work with "internal" because that is the kind of excitation I am using. I used the value of 2.52V because I routed the excitation to channel 0 and I could get the value.

With all of this in mind, when I try to run my strain task, I get a continuous line at -0.0365. I have also attached an image of the front screen panel as you requested.

I hope this is a better overall picture of my setup and of what I am trying to do. Do you think I can get the SC-2043-SG+6024E to work with a VI that used DAQ-mx drivers? Do you have a sample VI available?

[bgg]

Here is the screen shot

[Ana P]

Hi bgg,

The DAQCard-6024E supports the DAQmx drivers; therefore you should be able to develop your application using this driver. I understand that you are using the extended I/O cable instead of the MIO suggested in the knowledge base. So far, I don’t see any reason why it shouldn't work, more than the fact of the cable. Can you give us information on the DAQ drivers’ version that you are using for Traditional and DAQmx? Do you see the same behavior if you use another input channel? Can you run other tasks with the 6024E and the DAQmx drivers? Is this problem only with Strain tasks?