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The Record Page is used to view record digitized waveforms in real-time, store these waves to disk, load them from disk, and scroll through them post acquisition.  The Record page, illustrated below, is chosen by pressing the Record tab at the base of the instruNet World window.

Setting Up Channels
A display is shown for each Channel that has previously been turned On.  For example, in the above figure, one channel (i.e. "Ch1 Vin+") has been turned On.  To learn how to turn Channels On and Off, please consult Turning A Channel On.  The horizontal scroll bar is used to horizontally scroll through waveforms, post-acquisition, and consequently sets the time of the left edge for all displays.  The minimum display height is about 2cm, therefore if more displays exist than there is room, only a subset will be shown, and the user can vertically scroll through the viewed subset with the vertical scroll bar.

Setting Up Displays
Each display has a vertical axis minimum and maximum, as shown below.

The vertical axis is set up in the Display dialog. To access this dialog from the Network page, click on the channel of interest and then select Display in the Settings popup menu.

Alternatively, to access this dialog from the record page, click on the display label, which is pictured to the right.

The display vertical axis is in External Engineering units, as described here.

The Display dialog, illustrated to the right, provides 3 different ways to control displays:

  • Set top and bottom of display to specific values.
  • Set top and bottom of display to measurement min/max. For example, if you set up a thermocouple to measure 0 to 100°C, then the display will show 0 to 100.
  • Do not show digitized wave in the record page (Hide Display).

Digitize directly into RAM memory or a File on Disk?
For a discussion of this topic, please click here.

Oscilloscope or Strip Chart Scan Mode
instruNet supports two Scan Modes, Oscilloscope and Strip Chart, one of which is selected in the Scan Mode popup within the Setup Dialog.  Oscilloscope digitizes individual Scans (similar to a real Oscilloscope), whereas Strip Chart links a set of scans together, seamlessly, to form one long waveform (the user does not notice the individual Scans), as illustrated in Figures 5.1 and 5.2.  Put a little differently, Oscilloscope waits for a Trigger (specified in the Trigger dialog) before digitizing each Scan, and Strip Chart only waits for a Trigger before digitizing the first Scan.

Figure 5.1 Strip Chart Recorder Mode 

Figure 5.2  Oscilloscope Mode 

Oscilloscope mode has two variations, Oscilloscope and Oscillo Queued.  Both Oscilloscope and Oscillo Queued acquire and store scans of data in a buffer for processing.  In Oscilloscope mode the most recent scan of data in the buffer will always be returned for processing (first in, last out).  In Oscillo Queued mode the scans are retrieved from the buffer in sequence (first in, first out).

A typical example of how a data acquisition program using Oscilloscope mode would work is as follows: first the program would wait for the user specified trigger condition and then acquire the first scan of data; next the program would process the acquired scan (i.e. display, analyze, save to disk) while instruNet continued to acquire scans in the background based on the trigger condition, while the processing is going on; next the program would retrieve the most recent scan from the queue, ignoring older scans.

In the Oscilloscope case the scan returned from the buffer will always be the most recently acquired scan, and all other scans in the buffer will be ignored.  For example if each scan were 10ms long, the trigger condition was set to none, and the processing took 40ms, then the program would retrieve the first scan, process it and then retrieve the 4th of the 4 queued scans (i.e. the most recent scan) that had accumulated in the buffer while it was processing the first scan.  The 3 other older scans would be discarded. 

If the example above were done in Oscillo Queued it would work as follows: first the program would wait for the user specified trigger condition and then acquire the first scan of data; next the program would process the acquired scan (i.e. display, analyze, save to disk) while instruNet continued to acquire scans in the background based on the trigger condition; next the program would retrieve the next scan in the queue (i.e. the acquired scan that immediately followed the first acquired and processed scan).  In Oscillo Queued mode triggered scans continue to accumulate in the queue and are returned in order.

In Oscillo Queued mode all scans are returned by instruNet for processing but if a lot of processing is required between scans the instruNet buffer can eventually overflow at which point instruNet will return an error message.  In Oscilloscope mode the most recent scan is always returned and others are discarded.  While scans are discarded in Oscilloscope mode the buffer will not overflow.  If the time to process data takes less than the time of a scan then both modes will behave identically.  The below illustrations show the difference between Oscilloscope and Oscillo Queued modes.

Record Setup Dialog
The Record Setup dialog, illustrated below, is used to set the base sample rate, the number of points to be acquired per Scan, the number of Scans to be acquired, the recording mode (i.e. oscilloscope or strip chart recorder), the storage mode, and the display mode.  This dialog is described in detail in Digitizing Analog Signals into the Computer.

Timing Options
The Timing dialog, illustrated below, is used to set Fields that determine the digitization length and method.  This dialog is opened by pressing the Timing button inside the Setup dialog, and mirrors some of the settings inside the Setup dialog.

The Points per Scan, and the Number of Scans Fields specify the number of points (4bytes per point) that are digitized for each Scan, and the number of scans that are digitized when the Start button is pressed.  For example, if you digitize 100 pts/second, with 1000 points per Scan (i.e. 10sec per scan), and 10 scans, then your entire acquisition would consume 100seconds.  Pressing the Stop button will halt the digitization process, independent of where it is in its cycle.  The Scan Mode field was discussed in detail in the previous Oscilloscope or Strip Chart Scan Mode discussion.

The Record Setup dialog master Sample Rate field specifies the number of points digitized per second per channel.  All channels run at this rate unless their % Sample Rate Field in their General settings area has been modified from its default value of 100%.  This field enables one to run specific channels at a sample rate less than the master sample rate in the Timing dialog.  For example, if the master sample rate is 1000s/sec and a channel's % Sample Rate is set to 25, then the channel will run at 250s/sec.  The Network BPS specifies the network data transfer rate, in units of bits-per-second.  On power up, the network is set to the fastest possible rate. 

If the instruNet system reduces your sample rate to an unacceptable level, or your analog voltage data is too noisy, please see SAMPLE RATE VS. INTEGRATION VS. NOISE

Calibrate Options
The Fields in the Calibration Options dialog are used to specify Calibration parameters, as illustrated below. This dialog is opened by pressing the Calibration button, inside the Setup Dialog. For a description of each field, click here.

Display Options
The Fields in the Display Options dialog are used to specify Display attributes, as illustrated below.  This dialog is opened by pressing the Record button, inside the Setup Dialog, and mirrors some of the settings within the Setup dialog.

It is in the Options dialog that one specifies to Plot Dots or Lines, to turn the Grid On or Off, to set the horizontal scale (i.e. time per horizontal division), and to set the maximum plotting density (maximum points plotted per horizontal pixel).  Plotting Lines (i.e. connecting points with lines) takes more time than Dots, yet is easier to read if the points are far apart.  The Grid take some time to plot as well, and might not be desirable if you are trying to maximize your update rate in Oscilloscope mode.  If the horizontal scale (Horiz Scale) is too small (e.g. 10ms/div), the waveform might whip across the screen and be difficult to see in the Strip Chart mode.  The maximum points per horizontal pixel parameter is useful at plotting only a fraction of the digitized points in cases where you are digitizing ten's of thousands of points and don't want the computer to slow down due to plotting.  The Horizontal Position field is very similar to the Horizontal scroll bar in that it defines the time of the left edge of all displays.  If Overflow Alert is set to On, an Alert box is shown when a digitize buffer overflows (i.e. it fills faster than it is read); otherwise digitizing proceeds without an Alert. 

Saving Data
The Digitize Into field is used to determine whether waveform data is saved to To Ram Buffer, saved to To File, not saved (Off), or determined by the user (User Control). Each of these are described below in detail. For information on how to save a text file to Excel, post-acquisition, please click here. For details on maximum file and RAM buffer sizes, click here.

  • Off -- If the user selects Off, the waveforms are viewed while they are digitized, however you cannot scroll through them post acquisition (since the computer had not saved the data).  Since this does not consume memory or disk space, one could digitize many waves at a fast rate for a long time.
  • To Ram Buffer -- If one selects To Ram Buffer, each Scan is sent to RAM memory, which is limited by the amount of RAM that has been allocated to the instruNet World application program (or the calling application program in the case of calling the instruNet driver).  The buffer in memory holds only one Scan's worth of points, and therefore overwrites the previous Scan with each subsequent Scan.  If you are doing Strip Chart work and don't like this, set the Number of Scans field in the Timing dialog to 1, and the Points per Scan field to the value required to hold the entire acquisition.  Each point consumes 4 bytes since they are stored as 32 bit floating point numbers.  For example, 100K points would consume 400KBytes.  If you have just completed an acquisition with data being sent to RAM and want to save it to disk, press the Save button at the top of the Record page.  This will save all waves to disk.  You can then load the waves by pressing the Open button.
  • To File -- If you want to save all scans to disk, set the Digitize Into option to To File.  This will cause all waves to be spooled to disk as they are acquired.  If you are doing Strip Chart work, you can then use the horizontal scroll bar to scroll through the entire stream of data.  To load in data that was previously saved to disk, press the Open button and then select a previously saved wave in the File Open dialog.  Saving to disk is helpful if your waveforms are longer than available RAM.
  • User Control -- If User Control is selected in the Digitize Into field, then data will be saved per the settings in the User Ram Buffer, Driver Ram Buffer, and File Settings areas -- which are described later.

Trigger Options
The Trigger dialog is accessed by pressing the Trigger button within the Setup dialog.  This dialog is used to specify when digitizing begins after the Start button is pressed, as illustrated below.

The Trigger Mode field is used to specify no trigger (Off), Automatic trigger, or Normal trigger.  Normal trigger will wait forever until the trigger condition is met, whereas Automatic will trigger after several seconds even if the trigger condition is not met.  The Threshold EU field is used to set the threshold level, in engineering units, that the incoming signal must pass in order to trigger.  The Slope field sets the trigger condition for either a low-to-high pass through the threshold (Rising), or a high-to-low (Falling).  The Network number, Device number, Module number, and Channel number fields are used to specify the network address of the input channel that is to be used as the trigger source.  For example, {1,1,1,1} would specify the first channel within the first module in the first device tied to the first network.

Getting Ready to Digitize
Before you digitize, you might want to view the settings in the Setup dialog box, which is opened by pressing the Setup button at the top of the Record page.  This dialog's fields are described in detail in the previous pages.  In summary, one must specify the number of samples digitized per second per channel (i.e. "sample rate"), the number of points per scan, the number of scans, and weather or not the scans are continuous (i.e. Oscilloscope or Strip Chart Recorder mode).  The Trigger dialog is used to define when the digitizing begins (e.g. begin when the voltage at Channel #1 exceeds 3Volts).  In many cases, there is no Trigger, and the digitization begins when the Start button is pressed. 

To begin digitizing, press the Start button in the upper-left corner.  Waveforms will plot across the screen, in real-time, as they are digitized.  To stop digitizing, press the Stop button.  If the waves had been saved to Ram or Disk (i.e. via the Digitize Into field in Options dialog), then you should be able to scroll through your data with the Horizontal scroll bar.

If Your Sample Rate is Too Fast...
If the sample rate is too fast, an alert will appear notifying the user to a buffer overflow or sample rate problem.  This means the computer and/or Controller cannot keep up with the incoming data. In this case, you have several options:

  1. Reduce the master Sample Rate field in Record Setup dialog, or the number of digitized channels.
  2. Decrease the % Sample Rate field in a Channel's General settings area to decrease the sample rate for that specific channel.  For example, if you run 1 channel at 10% of the master sample rate, then its sample rate will be 1/10 of that of the other channels.
  3. Decrease the amount of plotting by reducing the size of the instruNet World window, plotting Dots instead of Lines (i.e. set the Plots field to Dots in the Record Setup dialog dialog), or reducing the plotting density by decrease the Max Pts Per Horiz Pixel field in the Display Options dialog.
  4. Reduce the amount of digital filtering in the Low Pass, High Pass, Band Pass and Band Stop settings areas.  Digital filters consume several microseconds to 0.1us per Filter Order, per point digitized.

Record Buttons
The Record Page sports the following buttons:

  Start digitizing channels that have been turned On.  Each channel is viewed in its own display.  The Digitize Into field in the Record Setup Dialog determines whether data is saved to RAM or Disk.

  Stop digitizing.  If the data had been saved to Ram, then one can now scroll through the most recent Scan, or save the Scan to disk by pressing the Save button.  If the data had been saved to Disk in Strip Chart mode, the user can now scroll through the entire set of Scans via the horizontal scroll bar.

  The Open button loads waveforms to disk that had been previously saved to disk during acquisition, or by the Save button after acquisition had completed.  The standard File Open dialog is used to select the specific wave file.  Since waves are saved in their own file, in one directory, it is necessary to only select one file, in order to load the entire set.  Once loaded, one can use the horizontal scroll bar to scroll through them.

  Saves to disk the current Scan in RAM memory.  The user is prompted for a directory name in which to save the set of data, where each wave is saved in its own file, in one common directory.  The data is saved in the fast instruNet Binary Merge format, multi-file Binary format, or slow generic text format; as determined by the File Type field in the Record Setup dialog.  If Text Merge is selected in the File Type popup, an additional "Excel Waveform Data.txt" text file is saved that contains all waves in one file, one column of text per wave.  This is useful when transferring data to a spreadsheet.  Binary Merge saves to disk faster than Binary, yet consumes more RAM memory.

  Opens the Record Setup dialog, as described in the previous pages.

  Prints the recorded waveforms to a hard copy printer, at the horizontal scale specified in the Record Setup dialog (i.e. which is mirrored at the front panel horizontal scale popup menu).  Multiple pages are printed, as required.  For example, if the waves are 100 seconds long, the horizontal scale is set to 1sec/division, and the paper is 20 divisions wide (each grid division is approximately 1 x 1 cm), then 5 pages will be printed.  If the horizontal scale is set to AUTO, the entire digitization is printed on one page.  Printing requires instruNet World PLUS (iW+).