Digital fault monitoring for single pair lines - using sampled oscillator signals and logic converters coupled to alarm stages

摘要

A monitoring system for two wire transmission lines in instrumentation systems is used to detect malfunctions, such as short circuits or line breaks. A sender station uses a multivibrator to control the transmission of an oscillator output over two switching gates onto the two wire line, over an isolating stage. Trailing edge detectors connect to an indicator. A receiver station is similarly structured and the signal generating oscillator output is periodically sampled and received. Any line malfunction is indicated by a steady logic level signal to the indicators.