I have not used the USB-9213 but notice from the manual that it has two modes: high-resolution and high-speed. The manual does not specifiy how to chnge modes - is says to read the help files. I do not have DAQmx, so I do not have the help files.
From looking at the data my guess is that the device defaults to the high-resolution mode which has a maximum sample rate of 1 S/s when using all channels. I suspect that your loop reads the same sample multiple times before the device updates the measurement.
Other notes:
- You do not need the sequence structure. Dataflow will give the same performance without it.
- The style guides recommend keeping the size of the BD (and FP) windows to the size of one screen. Scrolling to see what is going on slows programmer productivity and increases the chances for errors.
- Local variables should only rarely be used, and your program is not one of the places where they are appropriate.
- Consider converting to a state machine architecture. It is a more robust architecture, is easier to modify, and makes it mcuh easier to keep the BD to reasonable size. There are examples and templates which come with LabVIEW.
- Although it can probably keep up at 10 Hz, consider moving the data formatting and file writes to a parallel loop to avoid timing problems which can occur when the OS delays a file write, fragments the file or needs to allocate new space for a growing file. The Producer/Consumer examples/templates show how this can be done. Prodcuer/Consumer can be combined with the state machine I suggested above.
One other thing: Text files tend to be slow and large for the amount of data. Your data rates are not really very high and text files should be adequate. For faster performance look at TDMS files.
Lynn
