where can I find API for 6723 card and c examples

[TKNguyen]

where can I find API for 6723 card and c examples

[Dan_K]

Hello TKNguyen,

The NI 6723 is one of our MultifunctionDAQ devices and therefor uses our NI DAQmx driver.  The most current version of which can be found here:

Drivers and Updates: NI-DAQmx 8.8 - Windows 2000/Vista x64/Vista x86/XP

If you are using a version of Windows different than this, you will need to use either an earlier version of NI-DAQmx.  If you are using a Macintosh or Linux you will need to install NI-DAQmx Base.

Once you download the relevant version of NI-DAQmx and you install it you should be able to find the help file for the C API under your Start menu under All Programs»National Instruments»NI-DAQ»NI-DAQ C Reference Help.  Examples for programming NI-DAQmx applications in C can be found under C:\Documents and Settings\All Users\Documents\National Instruments\NI-DAQ\Examples\DAQmx ANSI C.  Of particular interest with your device would be the Analog Out folder in this directory.

If you are using a different operating system and/or are having difficulty using this API or these examples let me know.

[TKNguyen]

Hi Dan,

Thank you for your information.

After playing with examples in National Instruments\NI-DAQ\Examples\DAQmx and with 6723 card that I have.  It seems like 10KHz is the max frequency that I could generate from a AoX Voltage channel, even though I am runing a very slow sampling rate(2 sampling per cycle).  I guess my question is, what is the freq range that I could generate out from a channel on 6723 card.

Thanks

Nguyen

[Corby_B]

Hello Dan,

Thanks for your post!

The Max sample rates can be found on page 1 of the NI 6722/6723 Specifications manual. The Max sample rate for using one channel is 800 Ks/s and then goes down if using more channels. Let us know if this is the information that you were looking for and have a great day!

Cheers!

Corby_B

http://www.ni.com/support 

[TKNguyen]

Hi Corby,

I am sorry I don't know what is ks/s for.  Is it Kilo Samples per second?  If this is the case, I could generate a 100Khz at the 8 samples per cycle for a single channel? If not, how does this 800 ks/s max for one channel relates to max Frequency.  From the example ContGenVoltageWfm_IntClk, the max frequency I could get out of it is closed to 10KHz.

Thank you for your support.

Nguyen

[Corby_B]

Hello TKNguyen,

Thanks for your post back!

Yes, ks/s means Kilo samples per second so the card can do a max of 800 kilo samples per second for its Max output rate for one channel. However that doesn't mean that you can output a sine wave at 800 kHz. You usually want to follow the rule of 10. For instance when you are using an analog input you want to sample at least 10 times the frequency you expect to resolve the signal. The same goes for the output. So for the Max rate of 800 ks/s you could put out a resolved sine wave of about 80 kHz. If you go above that it could start to look more like a triangle wave or jagged sine wave. Let me know if this helps answer your questions/concerns. Have a great day!

Cheers!

Corby_B

http://www.ni.com/support 

[TKNguyen]

Hi Corby_B,

Thank you for your explainations.  Base on the infomation that you provided, It would be no problem if I want to generate a sine wave at 80KHz at 10 samples/cycle.

Please take a look at the example: National Instruments\NI-DAQ\Examples\DotNET2.0\Analog Out\Generate Voltage\ContGenVoltageWfm_IntClk .  This is my inputs for the application:

Physical Channel: "Dev3/ao0"

Mininum Value(V): -10

Maximum Value(V" = 10

Frequency: 80000

Waveform Type: Sine Wave

Cycles Per buffer: 1

Samples Per Buffer: 10,

Amplitude: 2.0

This is the error Message that I have got:

"Measurements: DAC conversion attempted before  data to be converted was available.

Decrease the output freq to increase the period between DAC conversions, or reduce the size of your output buffer in order to write data more often.  If you are using an external clock, check you signal for the presence of noise or glitches.

Status code: -200018"

Thank you for your support.

TKNguyen

[Corby_B]

Hello TKNguyen,

Thanks for your post back!

I am able to run this example in the .NET and LabVIEW environment without any problems. I know that at 10 samples per Buffer your sine wave has the shape it needs but what happens if you run the example with 5 samples per buffer? Do you still see the error. Also what else is running on your computer when running the example?  Also what kind of computer are you using? Have a great day!

Cheers!

Corby_B

http://www.ni.com/support 

Message Edited by Corby_B on 10-24-2008 11:39 AM

[TKNguyen]

Hi Corby_B,

Thank you for your quick responding.

Stil couldn't generate signal 80 KHz at 5 samples/buffer.

This is the error:

" Measurements: Onboard device memory underflow.  Because of system and/or bus bandwidth limitations, the driver could not write data to the device fast enough to keep up with the device output rate.

Reduce your sample rate, alter the data transfer method (from interrupts to DMA), use a product with more onboard memory, or reduce the number of programs your coputer is executing concurently.

Status Code: -200016 "

I am only running this program and outlook.  I am running on my labtop, xp window

Thanks

TKNguyen

[TKNguyen]

2.16GHz and 3.25GB RAM