发明名称 |
DIGITAL OUTPUT DEVICE DIAGNOSTIC METHOD, DIGITAL OUTPUT DEVICE AND PLANT CONTROLLER |
摘要 |
<p>PROBLEM TO BE SOLVED: To simplify system software by a self-diagnostic function, to diagnose a final output stage by the use of the minimum number of external wires and to attain multiple output constitution. SOLUTION: In the digital output device 1, plural contact output parts are connected by parallel constitution and a delay circuit 3 applies time differences to the state changes of respective contacts. When respective contacts are normal, a pulse signal is obtained from a contact voltage balance state detecting circuit 2. When a signal rise detecting circuit 7 detects the rise of the pulse, a one-shot circuit 8 is triggered and a one-shot output 17 is latched to a diagnostic result latching flip flop 4 based upon a latch signal 18 outputted from a diagnostic timing generating circuit 5 to obtain a diagnostic result 15. The result 15 is entered into a computer through a bus interface 12, and at the occurrence of a failure, the result 15 is outputted and separated as necessity so as to turn off a switch 11. Consequently the reliability of the contact outputs can be improved by the minimum number of plant side external wires.</p> |
申请公布号 |
JPH09146628(A) |
申请公布日期 |
1997.06.06 |
申请号 |
JP19950298455 |
申请日期 |
1995.11.16 |
申请人 |
HITACHI LTD;HITACHI PROCESS COMPUT ENG INC |
发明人 |
NAGAYAMA SHUICHI;FUTAHASHI YOSHIYUKI;KIKUCHI KENJI;NAGASHIMA HIRONORI;KURISU YOFUMI |
分类号 |
G06F13/00;G05B23/02;(IPC1-7):G05B23/02 |
主分类号 |
G06F13/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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