Using output buffer with 6009 or 6216 possible?

[kristel]

Hello,

I have a USB6009 and a USB6216. I need to generate a signal using the analog output and I would like to use the output buffer. My questions are:

- Does the USB6009 have an output buffer? I allways get some error, but from experience I know that this device is very limited, so I wonder if they just do not have any output buffer... (Buffered input programs are not a problem at all).

- I took the USB6216 and tried the example WfmGenUp.c  downloaded from somewhere in the Developer Zone (sorry I lost the link but attach the code) but I do not measure any signal in the analog outputs and after pressing Enter to stop the program (as required from that program) I get this error message:

NON-FATAL RUN-TIME ERROR:   "WfmGenUp.c", line 113, col 9, thread id 0x0000088C:   Function DAQmxStopTask: (return value == -200016 [0xfffcf2b0]). 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 computer is executing concurrently. Task Name: _unnamedTask<0>  Status Code: -200016

I do not know if the problem is just that the 6216 does not support output buffering either...

- So, if output buffering is not supported by 6009 nor 6216 what would be the best way to constantly generate signals at 100S/s?

Many thanks,

Kristel

[Marco_Brauner · Accepted solution]

Hi Kristel,

the USB-6009 has 150 S/s softwaretimed AO, so you won´t be able to use buffered AO with the module.

The USB-6216 does support buffered Analog Output, just follow the recommendations the driver gives you, 

for instance reducing the sample rate, if there is a memory underflow because of system and/or bus-bandwidth limitations.

Experiment with the settings and you´ll see in which range of samplerates it works.

You can find appropriate Examples in 

ANSI C:

C:\Dokumente und Einstellungen\All Users\Dokumente\National Instruments\NI-DAQ\Beispiele\DAQmx ANSI C\Analog Out\Generate Voltage\Cont Gen Volt Wfm-Int Clk

LabWindows CVI:

C:\Dokumente und Einstellungen\All Users\Dokumente\National Instruments\CVI\samples\DAQmx\Analog Out\Generate Voltage\Cont Gen Volt Wfm-Int Clk