Error -200077 when attempting analog output for NI 6703

[dmertz]

I am receiving the following error when attempting to send an analog output signal to my NI 6703 card:

Error -200077 occurred at Property Node DAQmx Timing (arg 1) in DAQmx Timing (Sample Clock).vi:1->AO to Mag Bearing.vi

Possible reason(s):

Measurements: Requested value is not a supported value for this property.

Property: SampTimingType
You Have Requested: Sample Clock
You Can Select: On Demand

Task Name: _unnamedTask<F>

I am attaching the VI.  Any suggestions would be appreciated.  Thanks.

[Sima]

What you're trying to do is hardware timing (the sample clock will try to setup the onboard clock of the device), which the 6703 doesn't support. Check out the datasheet of that card and you will see that it says static and software timed AO. So you can select the "On Demand" option, and you will then be limited to how fast you can spin your loop.

[dmertz]

Thank you!  That is what I needed to know. 

David

[Neal M]

Hello dmertz,

I would like to add some more specifics to what Sima said in the previous post.  The 6703 is one of our Static Output Analog Output cards, which means that there is no onboard timing oscillator to control output. This means that the computer must tell the card when to output a sample (which is "On Demand" timing), hence the software timing. The way your program is currently set up, the DAQmx Timing VI is trying to configure the onboard timing and can't find it so it throws the error.  The triggering VI will throw an error as well since your card does not support that either.

The most accurate way to control software timing is to use a timed loop.  You could also use a for loop or while loop with a wait function.  In the example finder (Help»Find Examples...), there should be an example that does what you are looking to do (with a while loop).  It is called Gen Mult Volt Updates-SW Timed.vi (under Hardware Input and Output»DAQmx»Analog Generation»Voltage).

If you do need hardware timing and triggering, NI has many cards which do support both.  If you let us know your requirements, we can make some suggestions or you can contact your Technical Representative who can help you find what you need.

[Tomaz79]

Hi,

I have a similar problem. I'm using a cDAQ-9172 chasis with a NI 9229 module. I'm trying to do single ponit continuous measurements with the DAQ assistant. I looked at the example Cont Acq&Graph Voltage-Single Point Optimization.vi for help, but the problem is that I cannot select the On Demand Acquisition mode, it's giving me the -200077 error

Property: SampTimingType
You Have Requested: On Demand
You Can Select: Sample Clock

Device: cDAQ1

The thing is, when I do a measurement, it's always measuring with a 1.6kHz rate, regardless what I put in the rate window. I can only change the number of points, but this only changes the duration of the measurement.

I'm trying to do voltage measurements about a minute long and I need about 10Hz sampling rate. The thing is I'd like to see what's going on during a measurement and stop it when I like, without having to set the appropriate number of points beforehand. Also, I'd like to use the data in external applications and with 1.6Khz sampling rate the large data files are a bit difficult to manage.

I hope you understand my problem and can suggest a solution. As you probably understood from my post, I'm a beginner.

Thanks!

[Paul_C.]

Hi Tomaz,

The NI 9229 uses a Delta-Sigma ADC that utilized oversampling to achieve better accuracy.  Therefore, the device is designed to be used with a specific hardware-timed sampling rate.  This is why the 9229 doesn't support on-demand sampling.  It only supports the use of finite or continuous sampling methods.

I hope this helps,

Paul C. 

[Tomaz79]

Hi Paul,

Thanks for your answer. So it's not possible to go around the 1.6kHz sampling rate? I can only define the duration of a measurement by setting the appropriate number of points at 1.6kHz? Is it possible to later discard unneeded data to write a measurement file with only 10 points per second?

Thanks!

[Paul_C.]

Hi Tomaz,

In the specifications document here, you can see the minimum sampling rate is 1.6KS/s.  If you try to select something lower, it will coerce you to use the 1.6KS/s.  Yes, you can definately discard unwanted samples.  I've included some pictures of how to do this below.   I used a divide by 200 to break a 2000 point array down to 10 samples.  In the DAQ assistant, I had it configured to acquire 2000 samples at 2KS/s.

I hope this helps,

Paul C.

Message Edited by Paul C. on 10-28-2008 09:38 AM

[Tomaz79]

Paul, thanks a lot. This works great!