| 摘要 |
A control system includes a microcontroller which receives input signals from input sensors and transmits output signals to electrically actuated solenoid valves in response to the input signals. A drive circuit controller is responsive to the output signals and to a solenoid enable signal generated by a watchdog circuit to control the solenoid valves. The watchdog circuit is responsive to watchdog pulses generated by the microcontroller and transmitted through the watchdog port of the microcontroller to generate the solenoid enable signal. The watchdog circuit generates the solenoid enable signal only when the frequency of the pulses generated at the watchdog port is within a relatively narrow frequency range. Accordingly, the watchdog circuit disables the drive circuits during failure of the microcontroller to assure that the solenoids will not be operated. |
