NETWORK PROGRAMMABLE LOGIC CONTROLLER SYSTEM WITH LADDER EDITOR AND PARALLEL AND SYNCHRONOUS LOGIC AND I/O SCANNING

A programmable logic controller system having the capability of controlling up to 64 clusters of peripheral controllers, wherein each cluster has up to seven racks of peripheral controllers, each rack having up to 16 individual peripheral controllers. Excepting for the cluster containing the programmable logic controller, each cluster is coupled to the programmable logic controller through an ethernet cable to a cluster controller. Each of the seven racks of peripheral controller cards is connected to its respective programmable logic controller or cluster controller directly (for the first rack) or through a local rack adaptor (for the other six racks). The programmable logic controller generates data, address and control signals which are used by the peripheral controllers to operate machines and equipment on an assembly line. The data, address and control signals are generated by a ladder diagram created and modified in a separate personal computer, which may be coupled to the programmable logic controller through an ethernet cable. The code representing the ladder diagram created in the personal computer is downloaded through the ethernet cable to the programmable logic controller. The ladder diagram is created and edited using a ladder editor program having the following features: scrolling, zoom in/out, free format line drawing, real time incremental compiler/linker, dynamic reconfiguration.