Input channel diagnostics

摘要

This invention relates to input channel diagnostics for an industrial process control system. The invention provides improved apparatus and methods relating to fault containment, overload protection and input channel diagnostics.

主权项

1. A method of internally testing an input channel for a safety critical system, the method comprising:
adding a subliminal perturbation signal to an input signal to be applied to an input circuit; detecting an output signal from the input circuit; and assessing operability of the input channel by determining whether addition of said subliminal perturbation signal causes a change in said output signal.