Title:
PROGRAMMABLE CONTROLLER
Document Type and Number:
Japanese Patent JPH04184503
Kind Code:
A
Abstract:
PURPOSE:To efficiently monitor the time of an external clock by comparing the time data of the external clock with the time data of an internal clock and, when the time difference between the time data of both clocks exceeds a permissible error range, outputting an alarm indicating the difference. CONSTITUTION:A time data comparing means 5 calculates the time difference between th time data of an externally provided clock 8 read by means of an external time data reading means 3 and the time data of an internal clock 2 read by means of an internal time data reading means 4 by comparison. A decision processing means 6 outputs an alarm signal indicating a large time difference to an alarm 7 when the time difference calculated by the means 5 exceeds a permissible error range. Therefore, the time of the external clock 8 can be monitored efficiently without periodical patrols of observers and, when the external clock 8 becomes abnormal, the clock 8 can be remedied immediately, because the alarm is outputted when the time of the clock 8 becomes abnormal.
Inventors:
SAITO KAZUHIRO
Application Number:
JP31476390A
Publication Date:
July 01, 1992
Filing Date:
November 20, 1990
Export Citation:
Assignee:
TOSHIBA CORP
International Classes:
G06F9/32; G05B19/048; G05B19/05; G06F11/30; (IPC1-7): G05B19/05; G06F9/32; G06F11/30
Attorney, Agent or Firm:
Takehiko Suzue (3 outside)
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