If you type "plot V(out)" to SmartSPICE it will try to start the SmartVIEW program. SmartVIEW is the Silvaco plotter. It is a good plotter with many features that you may like, but it is not part of SmartSPICE - it costs extra $'s.
You may want to use the plotter built into the Schematic - to do so simply ensure that these two lines are in your smartspice.ini file (see Setting Up SmartSPICE to be Driven from the Schematic):
set rawfiletype = binary
alias dplt 'write dplt.raw !:* ; shell start /min plot dplt.raw'
The first command switches to binary mode for file output. The second command alias calls for SmartSPICE to write out a raw file of whatever else is on the command line and then call for the Windows Shell to execute a command called plot ((you can in fact call plot from a cmd window or in a DOS script if you like and that will cause the schematic plotter to plot a file - as in "plot mydata.dat")).
So now in the SmartSPICE window you can type
dplt v(out)
And a plot of V(out) will appear in the schematic.
There is one more feature - if you would like to use the new hierarchical outline provided by Silvaco in SmartSPICE 2.24.3.R (and presumably later) to select data to plot and call for the schematic plotter as opposed to the SmartVIEW plotter simply add another line to your smartspice.ini file to make an alias for "plot":
set rawfiletype = binary
alias dplt 'write dplt.raw !:* ; shell start /min plot dplt.raw'
alias plot 'write dplt.raw !:* ; shell start /min plot dplt.raw'
Now the command plot itself will call for the schematic plotter.
Finally, you may want to turn this feature on and off. For example, to enable plotting to the schematic plotter type
alias plot 'write dplt.raw !:* ; shell start /min plot dplt.raw'
on the command line - now plot calls the schematic plotter. Then type
unalias plot
Now plot calls SmartVIEW again.