Warthog Systems LabHelper X
          hardware channel selection
            using LabHelper
After the sample rate is chosen in Chart mode or Oscilloscope plus Cart mode, the program 'loops', one channel at a time, through a series of windows that define the ACQUISITION PARAMETERS specific to each channel.  The panel at the top of the screen indicates which channel is being defined at the moment.  For each channel, select the following:

  •   A to D INPUT This links the 'logical' channel to a physical connector to the analog-to-digital converter (UI2, DataTaker, ADC-1, etc.).  You can select any of the A to D channels that are available, in any order; you may also assign a single hardware input to several logical channels.
                The A to D INPUT window looks more-or-less like this (the example is for the Sable UI2; the number of available inputs and other options depend on the specific A-D converter in use).

    Here, eight voltage inputs, four temperature inputs, and several other inputs are available. One (temperature channel T3) has already been selected, and the user has chosen voltage input 5 for channel 2. 

  • Note:  When using the ADC-1, you can set each channel to automatically adjust the gain function to maximize resolution (the default mode), or to use a fixed gain (of 1 or 50).  The latter option is slightly faster.

  • Streaming serial input

     A number of Sable Systems instruments (and others) have serial ouputs; these send a fixed-format string of digital data directly to the computer, avoiding the need for an A-D converter. Usually, several different variables are sent. LabHelper X knows the 'signatures' of some Sable instruments (the first part of the string contains an instrument ID), and can parse the string into the appropriate variables, with channel labels.

    In the following example, from the Sable RH-100 humidty sensor, the device provides humidity as percent relative humidity, dew point, and vapor pressure; it also shows internal temperature. You need to pick one of these variables to record. It's also possible to adjust the Y-axis scale on the plot; LabHelper X will make a guess for these limits.

    • (The 'update variables' button takes another reading from the instrument and updates the data fields)

    Note that most Sable serial instruments update their serial strings only once or twice per second, so it's inadvisable to use this option at high sampling rates.

  •   VOLTAGE CONVERSION     This defines the mathematical conversion that must be applied to the input voltage to produce the desired units.

  •    DISPLAY SCALING     This sets the Y-axis scaling for the computer's stripchart or oscilloscope display.

  •    SAMPLE AVERAGING     This sets the method and number of samples to be averaged for each recorded data point.

    Once all these values have been defined for the various channels, the acquisition parameters can be saved in a 'setup' file for later use.  This enables you to use the same sampling parameters without having to redefine them every time the program is run.  Setup files are saved from the OPTIONS window, or by using the M keyboard command (not available from certain windows).

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