This study develops and operating software for a model plant. The model plant consists of an AS/RS system, two machining centers, an assembly line, and supplementary material handling equipments. Devices of each component are connected with the IBS RT24 DIO 16/16-T I/O module. Each I/O module communicates digital signals with the INTERBUS controller board via SUB-D 9 Connector cable. This study is a previous stage for developing an educational CIM software. Petri Nets is used for modelling the storage/retrieval of the AS/RS system, the flow of workpieces and the assembly line for parts. The operating software is coded with Microsoft Visual $C^{++}$ 5.0 and Interbus Library which is a software driver for the controller board. The operating software can be run on a MS Windows 95. Microsoft Access is used for the implementation of databases for BOM, AS/RS, and parts.