Shared interface for multiple controllers

摘要

A control system for a balancing machine has a main computer with a keypad and monitor, an auxiliary computer for managing the balance measurement and correction functions and sharing the same keypad and monitor. Each computer controls the machine through a programmable logic controller (PLC). A video sharing circuit allows direct coupling of each computer to the monitor and includes a switching function under control of the main computer via the PLC to determine which computer will control the monitor display. A dedicated key command on the keypad controls the switching of the monitor control. Software in each computer responds to the dedicated key command for monitor control and also enables response to all other keypad commands by the computer which currently controls the monitor.