| 摘要 |
PURPOSE:To attain detection with high accuracy, without complicated software, by transmitting an output the polarity of which is inverted at each period of a diagnostic pulse applied externally from a specific output port, monitoring and detecting this operation through the relation to the diagnostic pulse. CONSTITUTION:Normally, a CPU2 has a runaway monitor program and inverts the polarity of an output signal B during the priod of a pulse A. An inversion detection circuit 3 transmits a pulse signal C at the leading and trailing of the signal B. Further, an FF7 is set when the signal A falls down, an output signal is reset at each input of the signal C and an output D is as shown in Figure (d). The signal D is not coincident with the signal A when the CPU2 is normal, signals E, F go to ''L'' to avoid the fail control and the reset of the CPU2. If the CPU2 runs away and the signal B keeps H, the signal C is not transmitted, the signal D goes to ''H'', the coincidence with the signal A is taken, the signal E is generated, a monostable multivibrator 9 is operative, a signal F with the specified pulse width is generated for the fail control and the CPU2 is set. |
