Title:
VARIATION RATE DETECTION METHOD FOR ANALOG INFORMATION
Document Type and Number:
Japanese Patent JPS6368907
Kind Code:
A
Abstract:
PURPOSE:To detect both long-period variation and short-period variation by comparing a sampled value obtained at a short period with a comparison reference value obtained at a period which is an integral multiple of said period, and obtaining variation rate information. CONSTITUTION:A CPU 3 reads a process value out of an interface 1 at every constant period. Then the current sampled value and a count value of the number of times of sampling are stored in a RAM 5 and the current sampled value is compared with the comparison reference value stored in the RAM 5 to check whether or not the absolute value of the difference between the both exceeds a prescribed variation rate limit value. Then when the absolute value exceeds the limited value, the variation rate is diagnosed as an abnormal value to output an alarm-on signal and when not, it the normalcy of the variation rate is judged to output an alarm-off signal. Then, the comparison reference value is updated into the current sample value at a reference value update period and the new comparison reference value is stored in the RAM 5. Consequently, the rate from long-period variation to short-period variation is securely grasped at every reference value update period and reflected upon the variation rate diagnosis.
Inventors:
KUMAGAI HIDEMI
Application Number:
JP21302686A
Publication Date:
March 28, 1988
Filing Date:
September 10, 1986
Export Citation:
Assignee:
TOSHIBA CORP
International Classes:
G05B23/02; G05B21/02; G06F3/05; (IPC1-7): G05B21/02; G05B23/02; G06F3/05
Attorney, Agent or Firm:
Kazuo Sato