This section uses graphics to present the rules of cycle-time, in an easily accessible form. The following figure shows how the software handles multiple time-stamps within a conserved-flow chain.
Cross level flows that are time stamped will track material as it flows through modules and maintain the time stamp on it.
Whenever a flow is time-stamped in a model, the software will automatically shift from the "Normal" to the "Cycle-time" Run mode. The change in the Run mode is required for the software to collect cycle-time information. The Run mode radio buttons can be found within the Time Specs dialog, under the Run menu.
Internally, the following changes occur as a result of shifting the Run mode from Normal to Cycle-time.
Practically speaking, you should notice only two behavioral changes when the Run mode shifts to Cycle-time. First, it is possible that the execution of a simulation run will be somewhat slower than might otherwise be the case. This is because of the additional calculational overload that is brought about by the generation of cycle-time metrics. Second, any stocks that have taken on negative values in the Normal mode (because Non-negativity has been turned "off" in their dialogs), will be kept from taking on negative values.
It's always possible for you to override the shift from Normal to Cycle-time Run mode. To do so, simply enter the Time Specs dialog and click on the "Normal" radio button. If you do shift to the Normal Run mode, cycle-time calculations will be disabled. As a result, cycle-time builtins will return a value of zero. All time-stamped flows will lose the clock face on their icons. Their check boxes will be turned "off." Similarly, all cycle-time converters will lose the clock face on their icons.
You can shift back to the Cycle-time mode by clicking on the Cycle-time radio button within the Time Specs dialog. Or, you can time-stamp any flow in your model. When you shift back to the Cycle-time mode, the software will remember all of your previous work with cycle-time. The clock face will return on the icons for all flows which had previously been time-stamped, as well as for all converters that contain cycle-time builtins.