200077 error lab view electrical stimulation

[viki_ua]

Dear Labview users,

My collegues and I are trying to develop a program in labview to apply rTMS (repetitive transcranial magnetic stimulation) to rats in an old version of labview (7.0).

We've started with a very basic blockdiagram, but even this one doesn't work. We keep on getting an error 200077 for the DAQmx Timing (use waveform).

They say we requested value 1, but only values >2 are valid. We don't know how we have to fix this. The printscreen is added, hopefully someone can help us solve this problem. 

Greetings,

[ThiCop]

Hello viki_ua,

Can you give some information about which kind of DAQ device you're using?

Can you send me a MAX Report of your system?

http://digital.ni.com/public.nsf/allkb/271F252B4EF0A2E0862570E70056A1E4?OpenDocument

[viki_ua]

Hello Thierry,

Thank you for replying so quickly.

Our labview version 7.0 does not have a MAX report function. I've tried to download max3.0 (because that's the oldest version) but I was unable to find the link. Can you tell me were I can find it?

[ThiCop]

Hello viki,

Normally a version of MAX (Measurement & Automation Explorer) gets installed together with any of the hardware drivers you install.
Do you have any hardware drivers (VISA,DAQ,...) installed?

[Akiel]

I think the fault lies in either the physical channel specified or the waveform generation. I have attached a working version but it refers to a card I have setup in max as a simulated device also the waveform generation is good enough to work prob not good enough for your application.

hope it helps

[Akiel]

just re read your post, I cant save it as a lv7 file so heres a screenshot of it

[ThiCop]

Hello Akiel,

In general this error means that you are trying to do something that is not possible/supported with the specified card.

To know if it is possible, we need to know what hardware is being used.

[viki_ua]

Hello,

Thanks for your responses. We are using a National Instruments PCI 6251 card.

We have tried Akiel's suggestion by simplifying the programme with a function generator (square wave).

When we try running the programme, we get this error:

Error -20061 occurred at Square Waveform.vi >> ma_Trap Fgen Parameter Errors.vi
frequency must be <= sampling rate/2

We want a pulse width of 200microsec (so an oscillation frequency of 5000Hz), repeated 60 times per second (60Hz pulse frequency) for a total time of 1h

You can find the new design in the attachement. Hopefully you can help us.

Kind Regards,

Viki

[ThiCop]

Hello Viki,

Your problem resides in the fact that you're only wiring the frequency input.
Fo this you specify the value 5000 (Hz).

This is an ok practice as long as you keep in mind the default values of the not wired inputs.

One of these inputs is sampling info and it contains two values:

- fs  = sample frequency which is by default 1000 Hz

- #s = number of samples which is by default also 1000.

So with these default settings it is not possible to create a square wave, because of the Nyquist theorem.
Are you familiar with the Nyquist theorem?

[viki_ua]

Hello,

Thank you for your response, the advise was very effective. The error has dissapeared when we adjusted the default value to 20000Hz.

The problem now is that when we measure the signal with an oscilloscope, the waveform is correct but

(1) the pulsewidth was 10ms in stead of the entered 0,2ms on the front panel

(2) it continues to send pulses without the interpulse interval dictated by the pulse frequency (60Hz)

(3) the stimulation doesn't stop after the total time (example: 10s)

(4) when the programme is stopped, a direct current is still send out, even after closing Labview (but stops when computer is shut down) 

Does any of you have a solution for any or all our problems? 

Greetings,