Data AcQuisition And Real-Time AnalysisScope - Spectrum - Spectrogram - Signal Generator
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Direct-To-Disk (DDisk) Toggle
This option allows continuous recording to disk of files of any length up to the 4 GB limit imposed by the .WAV format. (If you instead want to save only short single-screen files, use one of the "Save Trace As..." options in the File menu.)
All active channels will be recorded, whether they are currently displayed or not. If there are three active channels (say, two inputs and one output) the recording will actually contain 4 data channels, with the missing channel padded with silence. This is to maintain a standard .WAV file format, but this rule is used for .DQA and .DAT files as well.
DDisk recording can only be activated when there is something to record, so either Generator or Input, or both, must be active. The DDisk button will replace DD / Open on the main toolbar, and a disabled Record button will appear below the thin DDisk control dialog button.
Click the DDisk button to begin, or use the ALT+D keyboard accelerator. You may also use the File menu (ALT+F, D). A standard Windows Save As dialog will open allowing you to specify the file name and type. The default .DQA type is preferable since it includes all relevant channel calibration information and Notes, and is still compatible with most other .WAV software. However, you may use the Save as type control to select plain .WAV or headerless .DAT if you prefer.
After you select the file name, it will be shown on the title bar of the main Daqarta window for the duration of the recording. The Record button becomes enabled and a grayed-out file position readout appears below the right end of the trace area. The message line prompts you to toggle recording on and off with the Record button or the INSert key. The line above that shows the amount of Free Disk Space remaining.
Once the recording starts, a small red indicator square is shown on the depressed Record button, and the file position readout becomes active and shows you how much data has been recorded as the recording proceeds. The Free Disk Space line will also continue to be updated.
(Note that the file position readout units can be toggled between Bytes, Samples, and four different time modes via the small button next to the readout, or via "radio buttons" in the DDisk Controls dialog.)
Alternatively, before the Save As dialog appears you might be prompted to allow Daqarta to preset the maximum file size if you are low on disk space. Daqarta will attempt to maintain a reserve of about 1 MB of disk space, and will not allow DDisk recording to start if you have less than that.
During the recording Daqarta will actively monitor the remaining disk space and will end the recording early if needed to maintain the reserve.
You can suspend recording manually by toggling the Record button or the INS key. This does not pause the display, so you can continue to monitor activity. (By contrast, note that the Pause button only pauses the display, not the DDisk recording.) You can suspend and restart a recording as many times as desired; the actual file of the recording will contain only the active sections. This may be useful if you have periods of inactivity or spurious signals that would otherwise waste file space, and would take time to scroll through when viewing the file later.
When you want to finally end the recording, toggle the DDisk button off or hit ALT+D. You will be given the option to keep or discard the file.
From the DDisk control dialog (CTRL+D) you can set Write Size Preset to stop the recording automatically at a certain file length. You can also use Write PreStart to start the recording slightly before you hit the Record button or INS key!
The DDisk macro has no effect if any File Open or Save As dialog is already active, or if neither Generator nor Input is active.
DDisk= without a name will open the Save As dialog showing all .DQA files, and showing the default 'DDisk' file name.
DDisk="MyFile" will open the Save As dialog with the default name set to MyFile. (Note that quotes are needed around all filenames in macros.) If you accept this by hitting Enter or the Save button in that dialog, Daqarta will assume you want to save a file named MyFile.DQA. If that file already exists, you will be prompted to replace it.
DDisk="MyFile.WAV" or DDisk="MyFile.DAT" will open the Save As dialog as above, but with the specified extension, and that is the file that Daqarta will prepare to write.
After either of the above commands that invokes a Save As dialog, you may use IF.Posn?f=0 to see if the user has hit Cancel to exit without choosing a file name. This allows your macro to exit gracefully or take other action.
A.DDisk="MyFile" will prepare to save to MyFile.DQA directly, without any Save As dialog. Note that if the file already exists, it will be overwritten without any confirmation prompt. You can also specify the extension as above.
Similarly, if the Macro Variable Var0 holds a value of 12, then DDisk="Test"+Var0 will set a default file name of Test012.
DDiskRec=1 activates the Record button to begin recording data, and DDiskRec=0 stops recording. DDiskRec=x toggles the Record state.
To conclude the recording and save the file to disk, use DDisk=0 to toggle the DDisk button off. You will need to respond manually to the prompt asking if you want to keep or delete the new recording.
Alternatively, if you use A.DDiskRec to stop the recording before the DDisk=0, the prompt will be omitted and the file will be kept. Note that if you use DDiskPreset to allow the recording to end automatically, you will need to use A.DDiskRec=1 to start the recording if you want to omit the prompt.
You can obtain the current number of samples written by reading DDisk as a variable, as in S=DDisk. The value will be set to 0 when DDisk is first activated, before Record is active. Once active, the value will be the current number of time points, regardless of the number of channels per point. The final value will be retained even after DDisk is done, until the next DDisk activation.
You can read DDiskRec to find out if the recording is still running. The value will be 1 if the recording is in progress, else 0 if not started, done, or paused by toggling Record off (or using DDiskRec=0).
DiskSpace is a read-only macro that returns the current free space on the hard drive, in millions of bytes (megabytes or Mb). For example, A=DiskSpace will set macro variable A to 123456.789000 if there are 123,456,789,000 bytes free. You can use this at any time, not just in relation to DDisk recording.
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