The options on the Continuous tab in Preferences relate to SIMUL8 Process Objects.

System Dynamics Time Slice

System Dynamics Time Slice tells SIMUL8 how often it is to reassess flow rates and tank levels. Reducing this time will increase the accuracy of the simulation. If it is too small the simulation will slow down and may not increase in accuracy.

Visual Logic event System Dynamics Time Slice can be used to run code to be obeyed at each time interval. This can be used to “continuously” change rates of flow.

Note that all System Dynamics software emulates “continuous” because all modern computers are digital (not analog). This means that rates adjusted by the SD Time Slice Visual Logic are not actually adjusted continuously. A small time increment is introduced between each time the Visual Logic is obeyed. Tank levels and process states are updated when the visual logic inspects the tanks and adjusts flows.

This means that there is a small difference between true continuous simulation (not actually available in any simulation software) and the emulation of continuous provided by SIMUL8 Process and other System Dynamics software. This is important to understand because it is worth checking the accuracy level is sufficiently high for the particular simulation. In SIMUL8 Process the time interval can be reduced to increase accuracy.


Use the Units Measure box to select the measures most suitable for the situation under analysis. The unit selected does not affect calculations.