slight changes to vi needed

[cfm]

Hello,

Basically, I am a medical scientist with no background in computers or electronics and I have been given to .vi files which are used to measure and record small changes in voltage from a strain gauage and plot them as force (in dynes) against time. The problem is that these files were written years ago for use with a PCI 6024E and have a 9219. I have attached the files that I am using ( "single-channel2.vi" is the main vi and it will ask for "Max_Write_To_Spreadsheet_File.vi", "Max4_Input_Analogue_Single_Point.VI" and "Card_Setup.vi"). When I try to use this vi with my 9219 there are no readings, presumably because "Card_Setup.vi" is for the PCI 6024E. I have tried myself to replace "Card_Setup.vi" with my own .vi for the 9219 (see attached file "9219.vi") using the DAQ wizard but I don't know how to connect it to the main vi and even if I have set it up correctly. If anyone has the time to have a look at the set up and see how 9219.vi should be set up to be compatible with the rest of the vi it would be greatly appreciated. Incase it helps, the voltages being measured are between -4 and +4.

thanks,

Jamie

P.S as only 3 attachments can be added, some have been added to the subsequent post.

[Dennis_Knutson]

You need more than a slight change. You need a completely new VI. Whoever wrote the original, apparently use direct memory access to control the DAQ board. This is a bit 'strange'. The whole file write is completely wrong. After converting to a floating point number for display, this is then converted to an integer for the file write.

You VIs are in version 6 and I cannot save to that. A very basic acquire and save VI is shown in the attached picture. If you have access to a recent version of LabVIEW, I could post the actual VI but I hope the picture is enough.

Message Edited by Dennis Knutson on 06-19-2008 07:48 AM

[cfm]

Thanks dennis,
i have 8.5, i was just sent those files, if you could post that vi that would be great thanks,

Jamie

[Dennis_Knutson]

Sure.

[cfm]

Thanks for that Dennis,

When running that vi, and others that I've tried to make, I've found that it doesn't record the changes, it just gives a graph at the end with a downwards slope regardless of what's gone on while it's been running? Any ideas? Also do you know how to add the offset and calibration feature from the old vi I posted?

thanks very much for your help,

Jamie

[Dennis_Knutson]

I don't know what you mean by 'record the changes'. Do you mean that you are not getting any data written to a file?

As far as what is being plotted, you should check the DAQ connections and configuration with the test panel in the DAQ Assistant. I have no idea what type of signal you are trying to capture or how the DAQ board should be setup (i.e. RSE, Diff, etc). The old code was of absolutely no help in trying to determine that.You might want to post an image of the chart with some data being displayed.

You just have to insert numeric operators into the dynamic datatype wire where you want to. It seemed some of the operations in the old program were needed because it was getting raw, unscaled data from the DAQ board. The DAQ Assistant is normally set to return scaled and calibrated data.

[cfm]

Hi Dennis,

Yes there's no data written to a file. I've attached what I get displayed regardless of what the change in voltage has been and also the vi which I have slightly changed as it has been calibrated to display dynes, any ideas much appreciated,

thanks again,

Jamie

[cfm]

Hi Dennis,

Yes there's no data written to a file. I've attached what I get displayed regardless of what the change in voltage has been and also the vi which I have slightly changed as it has been calibrated to display dynes, any ideas much appreciated,

thanks again,

Jamie

[Dennis_Knutson]

Sorry but I cannot reproduce your problem. When I run the VI with my DAQ board (a PCI-6221), I get data in the chart and file. What do you see when you click the Run button at the top of the DAQ Assistant properties page? Do you have automatice error dialogs (Tools>Options>Block Diagram) turned on? You need to do this or wire up an error indicator.