DESIGN OF SAFETY CONTROLLER

摘要

A safety controller comprises a comparator and two identical subcontrollers operating on the same input signals. The comparator provides error detection by comparing the outputs of the two subcontrollers. Each subcontroller includes combinational devices and memory registers for providing exhaustive testing of the registers and of the truth tables of the combinational devices of each of the subcontrollers. Controllers of the present invention are particularly useful as railway safety devices.