synchronize two data acquisitions loops for tdms writing

[M.Riede]

Hello,

I have two different data acquisition loops. One slow CAN acquisition (10S/s) and a faster analog acquisition (30 samples at a rate of 300Hz) I need to synchronize these datas for tdms writing for further analysis in DIAdem.

Attached is my example and the result in the DIAdem channel list.

Many thanks in advance!

              Magnus

[REAL!]

Hi,

Do you mean that you wish to synchronise the start of the acquisition on both devices or that you wish to synch the timing of individual samples? For example do you need it that every 5th sample on the faster device the slower device takes a measurement?

Cheers,

Darren.

[Norbert_B · Accepted solution]

Magnus,

for a professional solution, you would want to synchronize the devices on a hardware level. Since CAN devices work way different to "traditional" DAQ devices, there are some important things to take care of.

Please look into the LV Example Finder for the keyword "CAN". You can e.g. select the example "Multiple CAN cards and DAQmx card Wfm Input".

Norbert

[M.Riede]

Hi Darren,

I need to synchronize the individual samples. I could also just copy each slow sample that often to have the same "sample rate" than the fast samples.

But I will also look at Norberts proposal.

Thanks to both of you,

       Magnus

[REAL!]

If it is possible I would slow the sample rate of the faster device to be an interger multiple of the slower device's sample rate, this will help avoid issues regarding the timing of the individual samples and provide a simple 'synchronisation' of the sampling. Providing they are triggered at the same time, obviously.

Using samples taken at the same time is important when doing calculations on the data set, if it is just for indication only then if it not so important.

[M.Riede]

Hello again,

thanks for the hint to the existiing examples in LabView.

I found one which fits perfect. IMPORTANT for me is the fact, that I can combine different sample rates for analog Data and CAN Data as the timestamps in the waveform-data perform the synchronization for DIAdem.

         Magnus