Error 1801

[Jaspal]

Hello All,

I seem to be having a problem with my VI and when I run ti, it displays an Error 1801 and teh description is as follows:

Error 1801: start value too large.

Possible reason: Hex (0XFFFFF8F7) Duration input is not an integer multiple of dt. VAlue coerced to nearest integer multiple of dt.

I have a VI which acquires signal at a sampling rate of 100Hz and processes it. This VI works properly.

However I have modified above VI to accpet data from another channel, now 2 channels, both sampled at 1Khz and this VI works fine too.

Now I have again modified this so that teh DAQ acquires both signals at 1KHz but one signal is resampled at a lower rate of 100HZ to work same as first VI. it is this VI that gives me the above mentioned error.

Strange that it only gives the error when I resample. but not when I ask the daq to sample at lower rate. I am using some functions of wavelet analysis in ASPT. I have no clue why this error occurs and have spent a few days trying things out. Can someone please help me with this.

Cheers,

Jas

[Hillman]

Hi Jas,

Good Morning and I hope your well today.

Thanks for your post. I have noticed you didn't receive any support for your issue. Are you still having problems?

If not, what did you change to fix it?

If yes, then could you attach your code? 

When you say re-sampling the waveform how are you doing this? in software or hardware? If you are performing AI DAQ tasks you could only have one AI Sample clock, and hence one acuqisition rate. If you wish to get a low rate, you can use on the resample VIs. 

Please update me when you can, 

[Jaspal · Accepted solution]

Hi Hillman,

Thanks for the post and sorry for not getting back earlier.

I tried resampling in software using resample.vi but this still gave me the error. I am using this signal to detect peaks and wanted to downsample to make it easier for the waveform peak detection.vi.

But eventally I ended up not resampling and increasing the width. This did get rid of the error but has introduced another problem which I am unable to sort.

The peak detection seems to miss a few peaks when the frequency of the signal decreases (i.e. when there are fewer peaks)

The sampling rate is 1000Hz and buffer size is 500 so every half a second the data is passed to peak detector vi and the width is 350.

This works fine for signals where the peaks are at 60-70 HZ but the VI misses peaks when signal is < 50Hz and it misses peaks randomly.

Any ideas what could be hapenning. I have attached the signal + peak for reference. Also the peak doesnt corealte with the proper peak, i thnikn this is beacuse of the width. If I reduce the width, I candetect the proper peak but I also detect the second small peak in the signal. Note that this pictur doesnt have a missed peak, but it is random. 

Dont know what to do..

Jas

[apiclab]

I'm getting this same error while using WDT Get Waveform Subset DBL.vi

The strange thing is that I've run all of my LabVIEW vis on an older version of LabVIEW flawlessly, and now that I have 2015 this error has occurred seemingly spontaneously... Does the updated LabVIEW software have anything to do with this error?

I still would like to resample my waveform, so any help would be appreciated...

Thanks everyone!