METHOD AND APPARATUS FOR ZONE SELECTION IN AREA MONITORING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an area monitoring device configured to enhance system safety by eliminating or reducing incorrect or inadvertent monitoring zone selection.SOLUTION: Zone selection logic in the area monitoring device increases the number of unique monitoring zone selections that can be selected using a limited number of discrete zone selection inputs, without compromising the safety critical operation of zone selection. The device monitors the logical state of each input in a set of individual inputs and recognizes each unique logical combination of zone selection inputs as a different zone selection. For example, each of two or more configured monitoring zones is associated with a different combinatorial zone selection pattern of asserted zone selection input signals. Correspondingly, a control circuit within the area monitoring device is configured to monitor the discrete zone selection inputs and activate a given one of the configured monitoring zones on the basis of recognizing the associated combinatorial zone selection pattern of asserted zone selection signals.