cDaq NI-9274 is slow

[ddean]

Hi,

I recently upgraded from Labview 8.6 to Labview 13, and now Labview 14 as well as to USB cDaq (9274) from PCI.  When I tried to upgrade a working vi, I experienced a lot of crashes.  So I stripped everything out of my program and I am now just acquiring data (5 channels) and displaying it.  It seems like it should be a very simple program, but a loop iteration takes over a second and after a couple hours takes over three seconds.  And it is still crashing when I shut it down. 

All I am doing is collecting two K-type thermocouples on a NI-9211, two voltages on another NI-9211 (C-type thermocouples) and a CJC from the second NI9211.  I am also converting the voltages to a temperature using a look up table. 

Does anyone have any ideas why this would be running so slow?

[ddean]

here is the vi lib

[natasftw]

You'd need to give us a whole lot more information than you've given us so far.

With the older version of LabVIEW, were you using the NI-DAQ or DAQmx drivers?  That would cause quite a bit of change.

Is there any reason you're doing the conversion yourself instead of just doing temperature measurements?  The 9211 can easily be setup with a k-type measurement just by choosing the temperature measurement rather than voltage.

What does "so slow" actually mean?  Realistically, you're not going to get anything faster than 14 Hz on a 9211.  This assumes you're using only a single channel.  If the program moves any faster, you're just repeating old data and not getting anything new.  Reading two channels on the 9211 drops you down to 7 Hz.  What are you sampling at? 

[ddean]

Hi,

I'm not even thinking about the old program now, just the basic program I described (aquiring and displaying data, 5 channels), but I was using DAQ Assistant with PCI cards. 

I'm doing the conversion myself because LabVIEW doesn't convert C-type thermocouples (?) and I want to validate my conversions with the K-type thermocouples.  I need to go to higher temperatures than K-type thermocouples can measure...

I am reading 1 sample (on demand) with the DAQ Assistant.  Slow means over a second for a loop iteration, with that time growing to over 3 seconds per iteration after running for 2 hours.  And crashing when I try to stop the program. 

I am adding an image of my entire program, since I can't seem to attach a file (maybe that's why I can't do LabVIEW - LOL).  Am I doing anything wrong?

Thanks for the help