Problems with acquisition on PCI-6259

[Cimteker]

Hi,

My application requires to scan all 32 AI channels. I am using a 4 Ms circular buffer with sampling rate of 50 000 S/s. Strangely I can only include 30 channels in my scan list. This line causes my application to stop working ( samples are no longer acquired, a call to

DAQmxGetReadTotalSampPerChanAcquired returns 0 )

DAQmxCreateAIVoltageChan(taskHandle,"Dev1/ai0:30","",DAQmx_Val_RSE ,-10.0,10.0,DAQmx_Val_Volts,NULL)

but it works fine when I use this line:

DAQmxCreateAIVoltageChan(taskHandle,"Dev1/ai0:29","",DAQmx_Val_RSE ,-10.0,10.0,DAQmx_Val_Volts,NULL)

I am using Visual C++ .Net.

Any ideas?

thanks,

jerry.

[e-Cash-Money]

Hello Jerry,

I created a simulated 6259 in MAX and ran a shipping example in 4 different ADEs (LV, CVI, VB .NET, C# .NET) and they all appeared to work correctly for 32 channel acquistion, so let's try these 3 things.

1) Try running one of the shipping examples in VB or C# .NET (or even ANSI C or Visual C).  Conifgure them to use the 6259 and all 32 channels.
C:\Program Files\National Instruments\MeasurementStudioVS2003\DotNET\Examples\DAQmx\Analog In\Measure Voltage\ContAcqVoltageSamples_IntClk
OR
C:\Program Files\National Instruments\NI-DAQ\Examples

2) Try creating a simulated device in MAX of a 6259 and do step 1)

3) Post your code here and we can test it out!

[Cimteker]

Thanks for your help.

The problem went away. I think I misunderstood the scan rate parameter and was trying to scan too fast ( over 1.25 MS/s ).

Jerry.