Simcenter Testing Solutions RPM Extraction in Simcenter Testlab

Simcenter Testlab



offline_rpm.pngDoing a test and don’t have a tachometer? Or don’t have time to instrument a tachometer? Have a system in which it is impossible to measure the RPM?

No problem! Simcenter Testlab and Simcenter Testlab Neo have you covered.

1. Offline RPM-Extraction in Simcenter Testlab
   1.1 Getting Started in Simcenter Testlab
   1.2 RPM Extraction Worksheet
   1.3 Selecting RPM Points on Colormap
   1.4 Saving the New RPM Trace and View Results
2. Extract RPM Method in Simcenter Testlab Neo

1. Offline RPM-Extraction in Simcenter Testlab

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In Simcenter Testlab "Classic", users can interactively click on a colormap to follow an order to define the RPM.

1.1 Getting Started in Simcenter Testlab

With the Offline RPM-Extraction add-in (Tools -> Add-ins -> Offline RPM Extraction, 20 tokens), it is possible to extract a RPM trace from the vibration or acoustic throughput data you collected.

Choose the throughput files of the signal you would like to track and replace in the input basket (Figure 1).

Figure 1: Replacing throughput data in the Input Basket.

Go to the Time Data Selection workbook. Ensure the “Data Source” is set to “Input Basket” then click “Replace”. The throughput channels that were put in the input basket will appear in the Data Set (Figure 2).

Figure 2: Importing the data into the Time Data Selection workbook.

1.2 RPM Extraction Worksheet

Go to the RPM Extraction worksheet. Select “Make trace list” to import the throughput data into this worksheet from the Time Data Selection workbook. Select which channel to use to calculate the time-tracked colormap by checking the box in the “Selected” column (a blue box will appear).

Then click “Calculate spectral map”. In the resulting colormap, it is desired to see a strong order that can be traced to determine the rpm. If necessary, change the processing setting for your map under “Settings…” until the desired order content appears as shown in Figure 3.

Figure 3: Bring in the data and create a spectral map tracked on time.

1.3 Selecting RPM Points on Colormap

Look for a strong order in the colormap.  By selecting points on this order, the rpm will be determined (Figure 4).


Figure 4: Selecting point(s) on order.If "One Point Method" (middle left) is selected, only on point is Accepted.

To select points along the order:
   A: Place the cross-hair cursor on an order.
   B: Click “Accept Point”. This will accept this point for the order calculation.

With the point  selected, now the RPM can be calculated (Figure 5).

Figure 5: Calculating the RPM.

To calculate the RPM from the selected points:
   C: Click “Predict Curve”. This will estimate the order trace and a black line will appear on the colormap where the order trace is estimated.
   D: Enter the order number of the order the cursor is placed on. This is essential to get the correct RPM trace.
   E: Click “Calculate RPM”.
   F: The RPM trace will appear.

NOTE: Under the “Processing” area, there are three method options: the “One point method”, “Two points method”, and “Multiple points method”.

  • One point method: predicts the order after accepting one point on the order line. The order curve is then predicted from the beginning of the time trace to the end. In this example, the order is well defined and the one point method works well.
  • Two points method: predicts the order after accepting two points on the order line. The order is only predicted between the two accepted points (it is not predicted from the beginning of the time trace to the end like with the one point method).
  • Multiple points method: predicts the order after accepting multiple points on the order line. This is useful when the order line is not very well defined. The order is only predicted between the lowest time value accepted point and the highest time value accepted point.

Try playing around with these different settings to see how they differ. Use "Clear All Points" button to reselect points from scratch.

1.4 Saving the New RPM Trace and View Results

Using the “Save” button, a new run will be created in the Navigator as shown in Figure 6.


Figure 6: Name and save the extracted RPM data.

To save the run with the calculated RPM:
    A: Name the run.
    B: Save the data.

Offline RPM extraction will not store data back into the original throughput run. To keep the original throughput channels in the run created in RPM Extraction, the throughput channels must all be added to the input basket and imported into RPM Extraction (see previous steps).

View the data in the Navigator workbook. The data will be stored in a folder with the run name that was typed in the RPM Extraction workbook. The extracted trace will always be named channel “5555: RPM Extr” (Figure 7).

Figure 7: Extracted RPM is stored with the name “5555: RPM Extr”.


Drag the extracted RPM into a plot to see what it looks like. For this example, the actual tachometer data was also recorded. Below is the actual tachometer data is compared with the extracted RPM. They are nearly identical (Figure 8).

Figure 8: The extracted RPM data (5555:RPM Extr) compared with the RPM calculated from the actual tachometer (1:Tacho1).


In Simcenter Testlab "Classic" the RPM extraction must be done one run at a time.  By selecting points individually, a high level of interactivity with the data is ensured. If the order is not strong over a certain RPM range, the user can select points manually to determine the RPM.

2. Extract RPM Method in Simcenter Testlab Neo

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With Simcenter Testlab Neo revision 2306 (23=2023, 06=June) and higher, an "Extract RPM" method is available in the Simcenter Testlab Neo Process Designer

The method is made available by selecting "RPM Extraction" under "File -> Add-ins".  It occupies 19 tokens when loaded.

The method can be used to automatically extract a rpm trace from operating data (Figure 9) to use with a spectral map or similar method.  This is very useful if there are strong clear orders that do not require manual intervention. 

User-added image
Figure 9: Simcenter Testlab Neo Process utilizing the "Extract RPM" method to automatically calculate a RPM from operating data for spectral map processing.


In the Extract RPM method properties, the following are defined (Figure 10):

User-added image
Figure 10: Method properties for Extract RPM.

Needed values include:

  • Identify the operating data (can be from pressure, acceleration, etc) to use to extract RPM.
  • Choose the initial RPM or frequency value for the strong order to use.
  • Name the RPM trace output by the method to be used in subsequent map methods.
Once defined, the process can be run on multiple runs at once.

Questions? Post a reply or email or contact the Siemens Support Center.

Simcenter Testlab Processing Tips:

General Knowledge Articles:

KB Article ID# KB000039988_EN_US



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