Wright Williams & Kelly
Factory Explorer® v2.2 Technical Alert #8
Summary: The shortest processing time dispatch rule (SPT) requires capacity analysis to function properly during the simulation. Normally, Factory Explorer® halts if a rule is being used that requires capacity analysis, and capacity analysis is not being performed. But in this case, Factory Explorer® does not generate a warning. This error is corrected in Factory Explorer® v2.3 beta 6.
Details: The SPT rule requires raw process times for process steps, and these times are calculated during capacity analysis. If capacity analysis is not enabled, the SPT rule is not able to correctly compare lots on the basis of processing time. Normally, Factory Explorer® halts if a dispatch rule is in use that requires capacity analysis, and capacity analysis is not enabled. In this case, however, Factory Explorer® does not generate any warning.
Workaround: If using the SPT dispatch rule, ensure that capacity analysis is always enabled (-DoCap) when performing simulation.