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Removing Zero Duration Capsules from Value Search on Numerical Step Signals


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Posted (edited)

Performing a value search on a numerical step signal is a common analytics workflow within Seeq.  For example, if a user wants to know when a control setpoint step signal is equal a certain value, they can use the Identify -> Value Search tool or write a simple Formula expression.  However, anytime the step signal crosses the value of interest, even for a brief instance, Seeq will generate an instantaneous or zero-duration capsule.  We can observe this visually in the following example when the Temperature Setpoint step signal crosses 160 F, our value of interest. 

image.png

Since we only want to know when Temperature Setpoint equals 160, we can address this by ignoring these unwanted, zero duration capsules. If the condition is defined using the GUI Value Search tool, select "Ignore short capsules/gaps" and enter a short duration for "Capsules shorter than".  It's important to consider the duration entered is smaller than any potential capsule you may be interested in for further analysis. For example 0.001 seconds.  

image.png

If the condition is defined using the Formula tool, for example: 

$signal == 160

we can apply the removeShorterThan(1ns) function to ignore all capsules shorter than 1ns. 

($signal == 160)
.removeShorterThan(1ns)

Using the temperature setpoint example, this would look like the following:

image.png

Edited by Dan FR
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