Setup before acquisition

[starcha]

    I am creating a small program for acquisition of EKG signal.. I want to leave some setup parameters open for configuring (DAQ channel, sampling rate....)
    I want to delay acquistion after setup. First to setup all parameters, and then to start acqusition,....

    Thank you in advance

[Otis]

Hi Starcha,

Could you give us a little more information about what hardware and software you have?  If you could, that would give us MUCH better information to work with and we could give you a better answer.

Just a few tips for general theory on measuring an EKG signal.

• The max frequency component in an EKG is about 300 Hz (in the QRS Wave), that means you need to sample at a rate >= 600 Hz. 
• Typically you will want some sort of signal conditioning before you try to input the EKG signal into the DAQ board.  EKG signals are very small, so the gain to pull it into the range you want may be 500-1000.  You will also want to filter the signal (Bandpass for 0.2 to about 200 Hz, Bandstop for 60 Hz noise).
• Make sure that you ground the EKG patient.  I spent hours once frustrated wondering why it wouldn't work, then I grabbed the computer in frustration...perfectly clear EKG.
• Isolation, use it.  Nobody likes being the short between your computer and ground.
  

That's all I can really think of for right now.  Best of luck, and let me know if you need any more info.

Regards,

[starcha]

I am aware of all those facts... this is just my final exam on faculty, and major problem, and aim of my part of work is introducing NI-DAQmx.. we allready have a working version of virtual EKG, but acquisition is done by an old PCI DAQ card (do not know exact model, it is not important) and now we are introduciny NI-DAQpad 6015, and we need to use NI-DAQmx (and we want).. so my question was just from LabVIEW point of view...  but I wish if you could give me some links or some e-material of EKG signal charcteristics.. it would be great... i do not have to "analyze" signal in any kind of way just to display it on monitor... do you have some advices about customizing chart display.. how to make it look as good as possible... i wish to make it look as similar as it get to paper version because it is easiest to work with for doctors used to that... it is easier to read... if you have some advices about that send it to starcha@neobee.net

[Otis]

Hi starcha,

Your question appears to be, "How do I make LabVIEW acquire my EKG."

That will be dependent upon your hardware.  Since you are using a DAQPad-6015, then all you need to do is open LabVIEW, go to the block diagram, drop down a DAQ Assistant, and read the data on the channel you want at the rate you want (probably around 1kHz).

Since you want to read the information on a chart that looks like an EKG chart, then you can just replace your Graph with a Chart and then right click on the chart (when viewed from the Front Panel) and change the Update Mode to Sweep Chart (Advanced > Update Mode > Sweep Chart).

You will still need to know the amplitude of the signal coming into the DAQ Board (must be less than or equal to +/-10V), how fast you want to sample, which channel you want to use (probably do differential mode on channel 0 (pins 68 and 34)), and you should make sure you isolate the patient from the computer.

Enjoy,