| 摘要 |
<p>PURPOSE:To surely monitor the change of an input signal even with use of a round-robin type operating system OS by using an exclusive sub-CPU to read the input signal and to store this signal in a shared memory. CONSTITUTION:A monitor 5c of a sub-CPU board 5 gives the commands to a system software 5b at each fixed time to read an input signal DI received from each working cell. Then the system software 5b stores each input signal into a map 5a. The contents of the map 5a are stored in a shared RAM 4 in the form of a message 4a. A main CPU board 1 can read the message 4a of the RAM 4 as necessary. Thus the processor of a main CPU board 1 can catch the necessary change of the input signal with use of a round-robin type OS even in an executing state of many tasks.</p> |
