Simultaneous continuous pulse train operation WITH synchronized Analog IO

[degenste]

Sean,

I have removed all the extraneous indicators and graphs, case structures, data logging, integration scheme, etc and all that is left is the DAQ tasks.  But I still have similar problems.  From my perspective the most frustrating problem is the Wfm acquisition not being stable.  If the peaks jump around on my mass spectrum then there is no way that I can collect useful data.  I am very confident that this is not a problem with the equipment, it is almost definitely a problem with the DAQ scheme I am using.  The peaks jump around when I run different programs or scroll the screen on my VI.  The problem you focused on in your last message to me was the Analog Read/Overwrite problem.  This actually dosen't happen very often (but I noticed that it happens almost immediately if I increase the number of points I am collecting (samples/scan) to a very large number, ~10,000, although this is much more than I need), and maybe it is the root cause of the wfm "jumpyness" I am seeing. 

Before I embark upon this master/slave architecture, I will try and solve the "jumpyness" problems by eliminating the ability to start/stop the AO mass scanning and writing data continuously.  If you have any other recommendations please give them.  Also if you see any glaring errors in my vi, they might be easier to identify now that the vi is much simpler.

Thanks,

Nick

Also tell me if my problem is not clear to you or if you need more info.

[degenste]

Sean,

I think that one of the problems, at least with the jumpyness might have to do with the "-1" value I have wired to the "# of samples per channel" terminal on my DAQmx Read vi ??

Nick

[Sean_C.]

Hello Nick,

That "-1" tells the DAQmx Read.vi to read all currently available samples from the analog input buffer.  If the rest of the code in your while loop takes too long to execute, there is a chance that your AI buffer could be overwritten before the DAQmx Read can be called again.  That seems more related to your overwrite error than the "jumpiness" you are seeing.

Can you provide a little more detail about this problem?  If you could send a screen shot of the behavior, that would be very helpful.

Also, can you try running one of the shipping examples to verify that this is a problem with your code?  Try running "Cont Acq&Graph Voltage-Int Clk.vi."  you can find this VI from LabVIEW by selecting Help >> Find Examples.  Then browse to Hardware Input and Output >> DAQmx >> Analog Measurements >> Voltage.  Does your Mass Spec signal still jump around?

Let me know you results,
Sean C.