Title:
GUARD TERMINAL DEVICE
Document Type and Number:
Japanese Patent JP3134859
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To eliminate the trouble to take countermeasure against a sensor fault by storing an operation time each time the sensor operates, finding the no-operation time of the sensor by subtracting the stored operation time of the sensor from current time if a guard mode is switched from a guard reset mode to an in-guard mode, and deciding whether or not the sensor gets out of order according to the no-operation time.
SOLUTION: When the guard mode is the guard reset mode and a sensor interface 2 detects a state change, a control part 6 reads the time of its operation out of a timer circuit 9 and stores the time in a storage part 11. When guard start operation begins, the control part 6 substrates the final operation time of each sensor stored in the storage part 11 from the current time to calculate the elapsed time from the time when each sensor operated last, i.e., no-operation time. No-operation times calculated by sensors are compared with a previously set sensor fault detection time to judge the possibility that a sensor has got out of order.
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Inventors:
Hiroshi Uchida
Application Number:
JP30917298A
Publication Date:
February 13, 2001
Filing Date:
October 29, 1998
Export Citation:
Assignee:
NEC
International Classes:
G08B23/00; G08B25/00; G08B29/04; H04M11/04; (IPC1-7): G08B29/04; G08B25/00; H04M11/04
Domestic Patent References:
| JP58204376A | ||||
| JP9231492A | ||||
| JP6243371A |
Attorney, Agent or Firm:
Nobuo Takahashi (3 outside)