Simulation Errors in Multisim When I Run My Simulation

Updated May 3, 2018

Reported In

Software

  • Multisim

Issue Details

When I run my simulation, I get a pop-up window with the following message:

"A simulation error has occurred. Would you like to run the Convergence Assistant to attempt to resolve this problem automatically?"
 

Solution

Simulation errors can arise for different reasons. To resolve these issues, first let the Convergence Assistant attempt to solve the problem. If it is not able to fix it, look for the following causes:
  • Floating components (i.e. parts with unconnected pins); these can go into the SPICE matrix, even if they are not being used, but can cause difficulties later
  • Extremely tiny resistor values; these enter the SPICE matrix as 1/resistance, creating large calculations
  • Direct voltage source across P-N junctions; this usually happens with LEDs and indicator components
  • Parallel voltage sources and inductors

If you are still getting convergence issues after checking for the above, your next step is to adjust tolerances. You can change the tolerances by doing the following:

  1. Select Simulate»Interactive simulation settings
  2. Select the Analysis options tab
  3. Click Customize ...
  4. Under the Global tab you can adjust the tolerances, using the following guidelines:
  • Increase RELTOL to no greater than 0.01
  • Increase VNTOL to no greater than 1e-3
  • Increase ABSTOL to no greater than 1e-6
  • Under the Transient tab, change the Integration method [METHOD] to Gear

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