Error -200278 with digital start and stop trigger

[theblueman]

Hi,

I'm trying to write a VI that writes the data from two analog input channels to a binary file and samples according to an external clock.  The program is also supposed to be started and stopped with a single digital trigger (acquire and write when high, stop when low).

I've looked at several examples (including Cont_Acq_Voltage_Ext_Clk_Dig_Start, Acq&Graph Voltage-Int Clk-Dig Start&Ref, and Acq_Graph_Voltage-Int_Clk-Dig_Start_Ref) but haven't been able to pinpoint my problem.  When I run my program, I get error -200278.

If I had to guess, I would say that the error might have to do with the reference trigger because I was able to get everything else to work besides that (see project-bak.vi).  The program was terminated by a stop button instead, but I'd like to set up the stop trigger if possible.

I'm using LabVIEW 8.0 with a PCI-6023E DAQ board.

Thanks in advance for the help as I'm relatively new to LabVIEW.

[theblueman]

After reading the Knowledge Base article "Error -200278 at DAQmx Read," I think I may have a conflict with my VI.  The article says to set the DAQmx Timing VI to continuous acquisition, as opposed to finite, in order to fix the error.  However, when I do so, LabVIEW instructs me that I cannot use a reference trigger with finite acquisition.  Any ideas on how to have both the start and stop trigger, collect data according to the external sample clock but only when the digital switch is on, and still avoid all errors?

[Travis G.]

Hello theblueman,

I found the following example program in the Example Code Library on ni.com.

NI-DAQmx: Continuous Analog Input with Both Start and Reference (Stop) Triggers

You should be able to modify this to use an external sample clock.

I hope this helps,

Travis G.
Applications Engineer
National Instruments
www.ni.com/support