CONTROL ALGORITHM FOR VERTICAL PACKAGE CONVEYOR

Three software programs are respectively run on the main processing constituent of a programmable logic controller (PLC), the network-controlling constituent of the PLC, and a human interface unit. Intelligent (e.g., switch, sensor, control, etc.) devices are distributed within a communications network associated with a vertical package conveyor (VPC). Signals are transmitted between/among the processing constituent, the controlling constituent, the interface and the devices. In an ongoing informational and regulative process, the devices provide input for the processing constituent, which in turn provides output to the devices. In furtherance of human safety, the processing constituent causes VPC operation to stop upon the occurrence of any of the following events: breached light curtain; open machinery access door; inoperable run stop button; inoperable emergency stop button; activated emergency stop button; misplaced package. The processing constituent also dictates the direction (up or down) and mode (constant or variable) of the VPC.