long simulation errors

[dbur]

Hi,

I have some long simulations to run and to get realistic resuilts I need to keep the timestep small.

I am getting simulation failures with 'internal simulation error'.

If I remove some variables it can go longer.

After the failure if I open the grapher it tries to graph the data but halts and restarts every 6-8 seconds and starts over -forever.  Each try it is able to plot some varying amount of the data.  The data is very good with the small timestep as opposed to longer timesteps, but it does not seem MS12 can handle the amoun tof data.

What are the limitations?  How many samples of how many variables can I accumulate and still have the simulation and grapher work?

Thanks.

[Miguel_V]

Hi,

there could be a few things going on with the circuit that might not allow it to run for too long (these mostly have to deal with the way multisim simulates circuits, theres always a few circuit design caveats depending on the engine running the simulation). Would it be possible for you to post the circuit so as to help you a little more thoroughly? Also the amount of time youd like to run the simulation for and your time step would be good information as well.

[_user32]

dbur,

Please try the custom Multisim VI called "Waveform Recorder" as it allows you to record any signal in interactive transient mode to disk (setup a sample rate, also your max time step (TMAX) should be smaller (<<) than 1/SR).   In this case there would be no limitation on how much data is recorded (along with the Waveform Recorder is a small application to allow you to navigate through the recorded samples).

Try it to see if it might satisfy your requirements.

Here is the link to this custom Multisim VI:

http://www.ni.com/white-paper/13715/en

Follow the directions on where to place the files so that it loads up when Multisim is launched.

Regards,

Pat Noonan

[dbur]

I tried the recorder, but is seems to only take up to four signals.  It also hangs MS after closing the configuration panel.

I have had better luck just saving a segment of the data I want.  i.e. I run a 50msec simulation but the first 40 msec is start up activity.  I tell MS to simulate 40-45 msec, and though it simulates the full interval it only stores the segment of data requested.  The grapher can then handle that.  At least it could until I tried to turn on sample display.  Then it never recovered and I had to kill MS and lost my overnight simulation data. 😞

The fine timestep simulation data is vastly more accurate than default timesteps or other values suggested in the forums.

I should think there should be a simulation option that forces finer timesteps when signals are active and stretches them out when static.  If I just set the simulation tolerances tighter does this do that?

Thanks,

David B

[dbur]

Afer hangin on this recorder twice MS then no longer would run.  Removing the recorder allowed it to run again.  I'll have to pass on this one.