The current simulation tools which are based upon stochastic queuing network architectures have proven to be inadequate for modeling modem Flexible Manufacturing Systems (FMSs). A Hierarchical, Object-Oriented Programmable Logic Simulator (HOOPLS) is proposed: to model the interaction among the controllers which coordinate the production in an FMS; to address the flow of all entity types including jobs, fixturing, tooling, and information; and to provide direct consideration of the detailed processing plans which govern how resources are employed to manufacture a given item within the FMS.

This paper discusses an object-oriented simulation project conducted for the United States Postal System (USPS) to test the reliability of an Ethernet LAN to support communication among various equipment contained at a General Mail Facility. The study was authorized by the National Institute of Standards and Technology to verify that the communication requirements derived from the implementation of their developed Postal Equipment Management System would not saturate the communication network. The simulated network handles over 400 transactions per second, and the USPS specified that eight hours of operation (one shift) must be simulated. The simulation was programmed in C++, and the completed study demonstrated that an Ethernet LAN can reliably support the communication requirements.