Error when generating waveform analog output on NI 6704 card

[Lelle]

Hi, I am trying to understand why NI 6704 card appears to be incompatible with what I'm trying to do. 

I want to use a waveform to generate an analog output voltage on a NI 6704. 

I have a vi in the style of the waveform buffer generator in this example:

http://zone.ni.com/devzone/cda/epd/p/id/4837

which creates the waveform. In my main routine I attempt to create and write a DAQmx ao task using the waveform information, but get this error: 

Possible reason(s):

Requested value is not a supported value for this property. The property value may be invalid because it conflicts with another property.

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

Task Name: _unnamedTask<7D>

According to documentation the 6704 has no onboard memory... but it's not clear to me how the DAQmx functions are actually sending the data to the card, i.e. if they are attempting to read and store the waveform buffer on to the card, it the lack of memory on the card could be my problem. Is is correct that that is part of my problem? Or since the error has to do with the sample timing clock, is my problem that the 6704  uses software timing? 

I've run my program successfully on an NI 6225 card... are there any work arounds for generating such an output on a 6704? 

Thanks in advance!

[Dennis_Knutson]

The error has everything to do with software timing. Your device does not have a hardware clock so you get an error when you try to configure it. To output a waveform, you have to do out one point at a time. You can only do this at a low frequency and it will have considerable jitter.