| 摘要 |
PURPOSE:To protect a device to be controlled effectively from erroneous control, by discriminating the malfunction of a control part to reset the control when the detecting output is not generated from the control part for a time longer than a constant time interval. CONSTITUTION:When a control part 1 operates normally, the detecting output of a specific pattern 11 is output at every constant time interval T for a constant period, and a output signal (a) of an AND gate 4 of the detecting circuit becomes low-level by this output. Therefore, a counter 5 counts the constant time (t) and is reset before overflow, and a reset signal (c) of the output is high-level still. If the detecting output of a specific pattern 11 is not output within a constant time (t) by runaway of a program, etc. due to causes such as noise, the output signal (a) of the gate 4 is high-level still, and the counter 5 overflows when counting the time (t) and generates the low-level reset signal (c), thereby protecting the device to be controlled effectively from erroneous control. |
