SIMPLIS outputs simulation data to data groups which are stored on disk as files. In this topic you will learn how to determine what data is output to a data group, how to change the current group, and learn when data groups are deleted.
To download the examples for Module 2, click Module_2_Examples.zip
In this topic:
This topic addresses the following key concepts:
In this topic, you will learn the following:
After every POP, Transient, or AC analysis, SIMPLIS stores the simulation results in a data group. Data groups are automatically named according to the analysis type, and to guarantee uniqueness, the group name is appended with an integer. When SIMetrix/SIMPLIS starts, the integer is set to 1, and the integer increments every time you run a SIMPLIS simulation. In the Manage Data Groups dialog above, there are three groups,
As discussed in 1.0.1 SIMPLIS is a Time-Domain Simulator, all the Time, for Every Analysis, Period, the transient simulation over-writes the POP simulation data. So in this example, you ran three simulations and from those three simulations, there are two data groups. The global group contains global variables used in the SIMetrix/SIMPLIS User Interface.
Each data group is completely independent of the other data groups. Each data groups contains the simulation vectors for that simulation, but no information on how those vectors were plotted on the waveform viewer. The plot journal method described in the 2.4.6 Using Plot Journals topic records how vectors were plotted and, when the you run the plot journal, the graph is recreated from the vectors in the current data group.
Data groups are stored in files on your local hard drive. Where data groups are saved and when they are deleted is set in the Options/Preferences... dialog. To view or change the location where the data groups are saved,
You can save the Temp Data to any location on your local hard drives.
At any time, only one data group is the "current group." The current group is the group which SIMPLIS uses to plot data from the simulation, or if you probe the schematic after the simulation completes. Since you ran a POP/AC/Transient simulation, the transient was run last and is therefore the current data group. You can change the current group to plot different simulation runs using the Manage Data Groups dialog. Just select the desired group and click on the Set Current Group button.
Data groups can be loaded from disk with the menu bar. This menu option will open a file selection dialog for you to open the data group.
A setting in SIMetrix/SIMPLIS controls when data groups are deleted. In the Options/Preferences dialog, on the Graph/Probe/Data Analysis tab:
The first three options are self explanatory, only the last option requires discussion. When data is no longer needed retains only the last three data groups. While this is the most aggressive setting, it is almost required for very large circuits or for simulations which are executed in a loop, such as DVM. For more information on this setting click on the Help button on the dialog.
The size of the data group is largely determined by two factors:
The number of vectors is determined by the Save options settings on the Choose Analysis... dialog. Below is the dialog for the 2.3_SelfOscillatingConverter_POP_AC_Tran.sxsch. The Save options group determines how many top level vectors are output to the data group. This setting applies to all analyses.
The three Save options apply to the top level circuit only. By default, the only vectors saved in hierarchical blocks are from probes inside those blocks.
To output vectors inside the design hierarchy, you use the .KEEP command in the F11 window of the hierarchical block. The next exercise demonstrates how .KEEP commands work.
Result: The mouse cursor symbol changes to a probe symbol:
1. No simulation has been run on that schematic 2. The wrong data is selected for that schematic. Use "Simulator | Manage Data Groups..." to select the correct data 3. The data for that node was not saved in that simulation
The reason for the error in this case is the third item: The data doesn't exist for the node which you probed, because you haven't told SIMPLIS to output the data to the data group. To output the voltages on the optocoupler schematic, follow these steps:
Now, probe the circuit again:
The following guidelines will be helpful to select .KEEP statements
|.KEEP *V||Keeps all voltages at this hierarchical level.|
|.KEEP **V||Keeps all voltages at this hierarchical level and all lower levels.|
|.KEEP *I||Keeps all currents at this hierarchical level.|
|.KEEP **I||Keeps all currents at this hierarchical level and all lower levels.|
|.KEEP *I **V||Keeps all currents at this hierarchical level and all voltages at this hierarchical level and all lower levels.|
|Other combinations are possible using a space separated list of voltage and current declarations.|
SIMPLIS creates output vectors in an orderly and consistent manner. At every topology change, SIMPLIS will add a data point to each simulation vector. In addition to these points, SIMPLIS adds uniformly distributed points from the simulation start to the simulation stop time. SIMPLIS adds the number of uniformly distributed points defined in the Choose Analysis... dialog on the Transient tab. Below is the transient tab for the 2.3_SelfOscillatingConverter_POP_AC_Tran.sxsch converter.
With these settings, SIMPLIS will generate 4000 data points evenly spaced over the 500us simulation time. Additional points will be added every time the circuit changes PWL topologies. The next example will help to better understand this behavior.
This measurement tells us the Inductor Current vector contains 5632 data points.
This message tells us the Inductor current vector contains 1634 data points. Note this is 3998 points less than the previous simulation where you added 4000 data point to the vectors. The constant offset of 2 data points represent the starting and ending data points. When you told SIMPLIS to output only 1 data point, the data group will only contain the points generated at every PWL state transition and the start/end points.
There is also an option to only output data at the Number of plot points defined in the Choose Analysis... dialog. The check box No Forced Output Data will only output the points set in the Number of plot points. No additional data points will be output when the PWL topology changes. Since the data group will not have points where the PWL topology changes, such as when a switch closes, using this option will reduce the fidelity of the output vectors and waveforms. This option is as two primary uses:
It is important to keep in mind that this option does not affect the accuracy of the SIMPLIS simulation, rather, the option affects the results output to the waveform viewer.
You can open an explorer window to the Temp Data directory (see Where Data Groups are Stored) to see the size of these files. Below is the Explorer window which displays the data group files for this section. The three selected groups are the transient results from the three exercises. Your data group numbers will be different if you have run more simulations than are explicitly called out in this section.
|Data Settings||File Size|
|4000 points, no .KEEP||4622 KB|
|4000 points, with .KEEP||4887 KB|
|1634 points, with .KEEP||1545 KB|
( not covered in class )