SIMPLIS Analysis Modes

SIMPLIS Initial Condition Back Annotation

After each simulation run finishes, SIMPLIS generates a file called the initial condition file. This file contains a sequence of SIMPLIS netlist commands that initializes a circuit to the state achieved at the end of the run. This allows a new run to continue from where a previous run completed.

Note: SIMPLIS creates this file for every run, including aborted runs.

The initial conditions file is, therefore, volatile and is overwritten during each simulation run. The file has the same name as the schematic with the extension .deck.init, and is stored in the SIMPLIS_Data directory.

The initial condition file can be applied by including it in the netlist for a new run; in some instances, this may be the most convenient method. However, it is also possible to annotate the schematic with the initial condition information. This has some advantages:

The initial conditions back annotated to top-level capacitors and inductors will also be recognised in SIMetrix simulation mode.
Back annotated initial conditions are attached to schematic instances and will be faithfully reproduced if, for example, a schematic block is copied and pasted to another schematic

How to Back Annotate a Schematic

To back annotate a schematic, select Simulator ▶ Initial Conditions ▶ Back-annotate from the menu bar. You will notice a second or two of activity in the schematic and then the operation is complete.

Note: SIMetrix/SIMPLIS does not distinguish between initial conditions that are back-annotated and initial conditions that are applied manually. After running the back-annotation algorithm, you will not be able to restore the initial condition value to those set previously. You can, however, use Undo in the normal way to reverse the back-annotation operation with a single Undo operation.

Disable/Enable Initial Conditions

To disable all initial conditions defined at the top level (not just ones that are back-annotated), select Simulator ▶ Initial Conditions ▶ Disable from the menu bar.

To re-enable initial conditions, select Simulator ▶ Initial Conditions ▶ Enable from the menu bar.

Back-annotation Errors

In order to apply back-annotation in a generic fashion, SIMetrix needs to modify the SIMPLIS_TEMPLATE property, but cannot do so if it protected, hence the following error message, which means that the SIMPLIS_TEMPLATE property is protected for the instances listed:
"The following instances have initial condition values but do not support back annotation."

You shouldn’t get this error with standard symbols from the SIMetrix libraries, but you may get it with your own symbols. To fix the problem, right click on the symbol, select Edit/Add Properties from the pop-up menu, and then remove the property from the symbol.

Editing Back-annotated Initial Conditions

Changing the value of an back-annotated initial condition depends on the device.

If the device is a capacitor or inductor or other devices that has a user-editable initial condition, use the standard method: select the symbol and press the F7 key or choose Edit Part... from the pop-up menu.
For devices such as subcircuit models and hierarchical blocks, which have no user-editable initial conditions, select the symbol and choose Edit Additional Parameters from the pop-up menu.

For more information about back annotation, see the following: