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Simulink Saving to Workspace Time is not monotonically increasing

Asked by Eric Cope

Eric Cope (view profile)

on 29 Jan 2013

I am running a simulink simulation using the fixed-step discrete solver. I've even specified the fixed-step size. I save some data via a "To Workspace" block (I've used the Scope to save to workspace as well with equivalent results). When I look at the time data in the object, the time is not monotonically increasing.

The time value is constant for 5-10 samples, then continues. Any ideas why this happens?

Thanks, Eric

http://i.imgur.com/NC37E5n.png http://i.imgur.com/S7XTQZh.png

4 Comments

Eric Cope

Eric Cope (view profile)

on 30 Jan 2013

The sample rate changes from 208MHz to 104MHz. Note that I received the same kind of data with or without the rate transition block.

Ryan G

Ryan G (view profile)

on 5 Feb 2013

What is the sample time in that 1/z block? What is the sample time in the to workspace block? What is the save format in the to workspace block?

 If it is sampling faster than it is receiving data, it will repeat values in the data.  
Chandrakanth

Chandrakanth (view profile)

on 7 Feb 2013

@Ryan G: Even if sampling is faster than update, data saved will be monotonically increasing although not strictly because of repeat values.

@Eric Cope: Do you mean monotonically increasing or strictly monotonically increasing? If you meant latter, its expected as Ryan explains. If its former, its intriguing - upload your model.

Eric Cope

Eric Cope (view profile)

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