Data acquistion after output with double buffer

[vtech]

Is there a way to acquire data that is being output by a double buffer? The code for double buffer is attached below. The way I am getting the data to the input channel is by wiring the input channel with the output channel. Once I have the data already in the input channel, how can I acquire it with CVI?

Thanks.

[LYu]

Hi vetch,

Double buffered output is a method of generating a continuous output by "dividing" the buffer into two halves to allow the buffer to be read and updated simultaneously. After wiring the output data into an input terminal, you can acquire this data in CVI by using shipping examples (found in Help >> Find Examples) such as ContAcq-IntClk.prj (Hardware Input and Output >> DAQmx >> Analog Measurements >> Voltage). If your board only supports the Traditional DAQ driver (older driver version), you can try the example attached.

If you need further information on Double Buffered Generation:
Continuous Waveform Generation [broken link removed]

Thanks,
Lesley Y.

[vtech]

Hi, Lesley.

Can the traditional library be used with DAQmx? I am already generating the data using the traditional library, but when I try to acquire it with DAQmx I get the following error:

" NON-FATAL RUN-TIME ERROR: "ContAcq-IntClk-AnlgStart_Fn.c", line 39, col 12, thread id 0x00000564: Function DAQmxStartTask: (return value == -200324 [0xfffcf17c]). Device not available in NI-DAQmx. It is possible that the device is being used by Traditional NI-DAQ or that the device is being reset. After using a device in Traditional NI-DAQ, you must reset the device before using it in NI-DAQmx. For SCXI devices, you must reset the communicator DAQ device. Call the Traditional NI-DAQ Device Reset VI or the Init_DA_Brds function. To reset all devices in Traditional NI-DAQ, right-click the Traditional NI-DAQ Devices folder in MAX and select Reset Driver for Traditional NI-DAQ. If you are resetting the device, wait for the reset to complete. Task Name: _unnamedTask<0> Status Code: -200324"

[LYu]

Hi vtech,

Unfortunately, it is not possible to use both the Traditional DAQ and DAQmx driver at the same time. If you're using the traditional driver with for data generation, you will need to use the same driver for the acquisition (if they're happening at the same time). You can find Traditional DAQ examples from:

C:\Program Files\National Instruments\NI-DAQ\Examples\VisualC\Ai

Thanks,
Lesley Y.

[Kevin_Price]

Just a brief expansion:

You can't use both Traditional DAQ and DAQmx at the same time for access to the same board. But you *can* use Traditional DAQ for calls to one board and DAQmx for calls to another in the same app. I've got a working app doing this because one board is only supported by Traditional DAQ and another is only supported by DAQmx.

I don't think this was a point of confusion for the original question -- I just wanted to clarify for the sake of future readers of the thread.

-Kevin P.

[Badel12]

Device not available in NI-DAQmx. It is possible that the device is being used by Traditional NI-DAQ or that the device is being reset. After using a device in Traditional NI-DAQ, you must reset the device before using it in NI-DAQmx. For SCXI devices, you must reset the communicator DAQ device. Call the Traditional NI-DAQ Device Reset VI or the Init_DA_Brds function. To reset all devices in Traditional NI-DAQ, right-click the Traditional NI-DAQ Devices folder in MAX and select Reset Driver for Traditional NI-DAQ. If you are resetting the device, wait for the reset to complete. Task Name: _unnamedTask<0> Status Code: -200324"