VIEW menu

  •   SCREEN COLORS     Lets you select colors for chart and oscilloscope screens from the standard Mac color wheel.  Obviously, this option is not available on monochrome monitors.  Color preferences can be saved for automatic re-use the next time the program is launched (use the SAVE PREFERENCES menu selection).  This option is deselected unless color is in use.

  •      TIME GRIDS submenu     These submenus control the display of vertical (time) grid lines:

  •   SHOW TIME GRID     Activates or deactivates the display of time grids and tics in plot areas during data acquisition.

  •    DASHED GRID LINES     Toggles between dashed and solid grid lines in plot areas.  NOTE: this option is deselected unless SHOW TIME GRIDS is 'on'.

  •   DASHED MARKER LINES     Toggles between normal (dashed) and solid marker lines in plot areas.  During chart file acquisition, markers appear when individual keys are pressed.

  •      SCALE GRIDS submenu     These submenus control the display of horizontal (scale) grid lines:

  •   SHOW SCALE GRID     Activates or deactivates the display of time grids and tics in plot areas during data acquisition.

  •   MANY GRID LINES     Toggles between normal and high-density grid lines in plot areas.  NOTE: this option is deselected unless SHOW TIME GRIDS is 'on'.

  •   SHOW ZERO LINES     Toggles between visible and hidden zero lines in plot areas.  These indicate the position of zero, if the data range includes zero.

  •      WINDOW SIZE     On a large screen, these submenus allows use of several window sizes:

  •      SET WINDOW AREA      This option (only available if the screen is bigger than 640 X 480 pixels -- as is true in all modern computers) lets you set the display window size by dragging a window to the desired shape. It will not allow a display size smaller than 640 X 480 pixels, and the window is always in the upper left corner of the screen.

  •      640 X 480, 800 X 600, 832 X 624, 1024 X 768     Sets the display window size to a specified number of pixels, in the upper left corner of the screen.

  •      FILL SCREEN     Sets the display window size to fill the available screen area (no part of the desktop is visible when gathering data).

  • Top of page

  •    PLOT HEIGHT     (not accessible in Multichannel Oscilloscope mode) allows you to divide up the vertical screen area among the different channels according to your own preferences.  For example, you can show some channels in large vertical scale and others in much smaller scale.  Note that because there is a fixed amount of screen space available, making a channel larger than normal requires shrinkage of other channels:

    To set channel heights, move the cursor up and down within the simulated plot area until it is at the desired height, then click.  The program steps through the channels in sequence.  When all channels are complete, you can accept the results, use normal values (all channels with equal heights), or redo the selection.

    The program tries to reserve a minimum amount of space for any remaining channels (20 pixels high), but slightly more space will be needed if you are using alarms or device switching (the notification textfields for these occupy more than 20 pixels of vertical space).  Channel heights do not affect other aspects of the data acquisition process.

  •   CHART VIEWS AND TICS...      G     opens a window that allows selection of the 'density' of data plotted in chart mode and, if the maximum number of samples exceeds the width of the DAQ window, the method of scrolling data:

    The normal view contains one sample per pixel on the x-axis.  However, you can select compression ratios of 2, 2.5, 4, 5, and 10 (these options are available only if the number of chart samples is greater than the number of samples per screen).  Thus with a 640-pixel-wide screen, up to 6400 samples can be shown on a single screen.  The range is 832 - 8320 when using an 832 pixel-wide screen, and so forth with larger screen sizes.

    Using the more compressed views increases the amount of recording time that fits on the screen, but at the same time the screen resolution is decreased (for viewing only; not recording) because several samples are plotted within the same x-axis pixel position.

    Some combinations of view compression and maximum sample number may generate fractional time units on the X-axis of the chart display.  However, you can manually adjust the scaling of the 'time tics' on the x-axis (if they are used) with the 'use custom tic unit' button (this is automatically selected if you click in the adjacent edit field).

    If the number of samples is greater than can be shown on a single DAQ window, the chart display must be scrolled when the data plot reaches the window's right edge.  The default scrolling value is 100% -- that is, the entire window is redrawn, showing none of the previously-acquired data.  Alternately you may select fractional scrolling (50%, 67%, 75%, or 90%), which leaves some of the previously-acquired data in view.
            Another option, which works only at low sample rates, is 'Continuous' scrolling.   In this mode, once data lines reach the right edge of the DAQ window, the window is scrolled one pixel at a time as additional data are obtained.   If you sample too fast, data will be acquired -- and can be saved --successfully, but the display updating will 'get behind' and seem to pile up at the right edge:   display updating will lag behind data acquisition.  The program will let you do this but it may be cosmetically ugly and confusing as well.   The sampling rates that cause this problem depend on the number of channels, the speed of the computer's graphics engine, and other factors, but very roughly, you can expect normal function with 6-10 channels if sampling rates are slower than 2-4 samples/sec.

  •   SCOPE VIEWS AND TICS...      opens a window that allows selection of the 'density' of data plotted in chart mode.  It is similar to Chart view, except that it offers options to display only a fraction of the gathered data (all the data will be saved if a file is stored).  Reducing the number of points displayed can greatly increase the display rate (and hence the fraction of total time spent in sampling data) -- although this is rarely a limitation with fast, modern Macs and relatively slow A-D converters.  For all practical purposes, you should use the "show every point" option.

    Top of page

  •   STATUS DISPLAYS     At most sampling rates, LabHelper provides several status displays on the data acquisition screen.  These include the numeric variable value readouts in chart channel panels.   Updating these during acquisition requires some cpu and display time, and they occupy some screen space, so they should be turned off when you want to use very high sampling rates.

    In practice, this often has only a minor effect because the biggest constraint on sampling rate is the speed of the A-D converter, and how fast data can be transferred over the serial interface linking the converter to the computer.   However, if the DAQ window is wide (e.g., >1200 pixels), the number of channels is large, and the sampling rate is high, turning off channel status readouts can make the graphical display update more smoothly.   It might also be useful to switch status displays off if you want a 'cleaner' picture of the graphical display of DAQ results.

    Use this window to adjust the 'cutoff' sampling rate above which status displays are switched off (you can also instruct LabHelper to leave them on or off at all speeds).

  •   SHOW SWITCH STATUS     Activates or deactivates a display of the external device control status during data acquisition.  This shows whether a particular channel's device is acquiring sample data, reference data, or is inactivated (zeroed).

  •    In addition to the graphical display, LabHelper shows digital readouts of channel values during data acquisition.  The LARGE READOUTS option toggles between the normal size digital readout displays (in 10-point type) and a much larger display (in 20-point boldface) that is more easily visible from a distance.  Note that if you have selected a very small plot height for a particular channel, a large-format digital readout may not fit.

    Top of page

  •    ALWAYS SHOW HELP DATA     When this option is checked, the 'help' data for various windows and operations (normally selected with the '?' button) will be shown by default.
    •    OPEN HELP WINDOW     H      opens the general Help window.

  •    SIGNIFICANT DIGITS     Lets you select the number of significant digits in numeric displays (this has no effect on the precision of recorded data).

    Top of page

  • Other links: