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Time Signal Calculator Tips!

by Siemens Experimenter Siemens Experimenter ‎07-11-2016 09:14 AM - edited ‎11-02-2016 10:56 PM

Using LMS Test.Lab Time Signal Calculator?  Here are some tips for you!

 

The LMS Test.Lab Time Signal Calculator is loaded with functions to condition and perform calculations on time files. 

 

Operations include filtering, integration, envelopes, rosette, math, logic operations and more!

 

Getting Started

 

To turn it on, choose “Tools -> Add-ins -> Time Signal Calculator”. 

 

Picture 1: From the main menu, select "Tools -> Add-ins -> Time Signal Calculator"Picture 1: From the main menu, select "Tools -> Add-ins -> Time Signal Calculator"

Go to the “Time Data Selection” workbook and load up some time history data:

 


Picture 2: Select the "..." button and select data from Input Basket or Active Project.  Push "Add" or "Replace" when done.Picture 2: Select the "..." button and select data from Input Basket or Active Project. Push "Add" or "Replace" when done.

 

  • Click on the button with “…” in the upper right to select time data from either the input basket or the active project
  • Click “Add” or “Replace” to make the time data active

The time data is now available for processing.

 

Picture 3: Data channels in list ready to process.  Each has a Channel Identification assigned (CH#)Picture 3: Data channels in list ready to process. Each has a Channel Identification assigned (CH#)

Note the following about the time data list:

  • Green color – Indicates data is stored permanently on disk
  • Orange color – Data is available for processing, but not stored permanently
  • “Save As…” – Used to permanently store time data to new file. Your orange data traces should turn green after using this.
  • “Save” button – Used to permanently store time data to existing file. Your orange data traces should turn green after using this.

Formulas can be entered in the Time Signal Calculator to manipulate data in the list.

 

Picture 4: Formula area of Time Signal CalculatorPicture 4: Formula area of Time Signal Calculator

 

When creating formulas in the Time Signal Calculator, there are three key fields that can be filled out:

  • Id – The destination channel identification for the operation. If left blank will automatically fill in with next available empty channel identification.
  • Formula – The math or function operation to be performed
  • Point Id – The resulting name of the new time history/channel

 

Math Operations

 

Once channels are loaded, notice that they are assigned identifications, for example, CH1, CH3, etc.  CH is short for Channel.

 

The math operations ( +, -,   /, * ) can be used with these identifications. 

 

Picture 5: Data set (upper) and formulas (lower)Picture 5: Data set (upper) and formulas (lower)

 

Examples:

  • CH5+CH6 -  Will add channels 5 and 6
  • 100*CH5 -  Scales channel 5 by 100

When doing these operations, it is not necessary to use the assigned channel identification.  Instead, one can use the Point Identification:

 

  • oilpan+left_head -  Adds channels 5 and 6 which have Point Identifications “oilpan” and “left_head”
  • oilpan+CH6        -  Adds channels 5 and 6

The desired engineering unit can be assigned to the result of any math operation. Use the bracket signs to assign the unit, for example [g]

 

  • (CH5+CH6)[g]

To ensure the data is handled properly, the assigned unit needs to be a valid unit that exists in the LMS Test.Lab Unit system.  If you are not certain what units are valid, go to “Start -> Programs -> LMS Configuration and Unit System…” to get the available list. Note that the units are case-sensitive. 

 

Picture 6: Warning/error due to specifying uppercase "G" (not in unit set) rather than lowercase "g" (in unit set)Picture 6: Warning/error due to specifying uppercase "G" (not in unit set) rather than lowercase "g" (in unit set)

There will be a warning if the unit specified is not available/valid, and the status on the formula will be colored red.

 

F_keys.png

 

 

 

Create additional cells for formula using F key with a yellow star.  There is no limit to the number of formulas.  You can also delete the formulas using the F key with a red X.

 

save.png

 

 

To save formula sets and recall them for later, use the buttons.

 

Advanced Functions

 

In addition to math functions, many other operations can be performed on time data.  To access the other functions, highlight the cell for which to create the functions and press the button with “f(x)” showing on it.

 

Picture 7: Creating a new formula with the "f(x)" button.Picture 7: Creating a new formula with the "f(x)" button.

A list of functions appears.  The left side of the menu are categories for the functions, while the right side is the list of individual functions.

 

Picture 8: Time Signal Calculator formula list.  Function group on left, individual functions on right.Picture 8: Time Signal Calculator formula list. Function group on left, individual functions on right.

 

As an example, to create a high pass filter, select the FILTER_HP function.

 

Picture 9: The HP_FILTER formula menu entry.Picture 9: The HP_FILTER formula menu entry.

For a filter function, the following can be filled in:

  • Function1: Enter channel identification or point identification name
  • Freq: Enter cutoff frequency for filter
  • Filtermode: Can be 0 or 1, depending if you direct or zero phase filter is desired
  • Type: IIR or FIR
  • Method: Multiple types of filters
  • Order: Higher this number, sharper the filter

Information about these fields are found in the software help.

 

Press “OK” when finished.

 

To perform the filtering operation, press the “Calculate” button to perform all functions in the list.  “Calculate Selected” can be used to perform only the highlighted function.

 

Other Functions

 

Other popular processing functions include:

  • RESAMPLING – Resample data to higher or lower sampling rate, with anti-aliasing filter
  • INTEGRATE – Transform acceleration time data to velocity or displacement
  • DIFFERENTIATE
  • FILTER_HP – Create high pass filter
  • FILTER_LP – Create low pass filter
  • ROSETTE – Perform rosette calculations on strain gauges
  • TACHO_PULSE_TO_RPM – Convert pulse train to rpm
  • BOLT – Calculate principal stress and strain

 

Multiple Functions

Sometimes the same operation may need to be performed on multiple channels.  However, it is not necessary to create 20 separate FILTER_HP functions to filter 20 channels.  This can be done in one step.

 

 

Picture 10: Performing operations on multiple channels with a single formula.Picture 10: Performing operations on multiple channels with a single formula.

Here is how:

  • Enter the channel number as “CHX” where X is a place holder for the channel number.
  • Enter a range of channel numbers to be used for X into the field called “Repeat for…”.
  • By entering “1:20” in the “Repeat for…” field, channels 1 thru 20 will be done in one step.
  • If there are channels without data in the range of 1 to 20, no problem! They will simply be ignored.

Note that the “Repeat for…” field may require using the slider bar in the lower left corner to scroll over to see the field.  It may not be visible by default.

 

Questions?  Contact us!

 

Related Links:

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LMS Test.Lab Display Tips:

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