| 摘要 |
PURPOSE:To improve the reliability of process control by sending an address and data having the same contents as the address from a processor to a digital output device through a bus and comparing the address with the data through the output device. CONSTITUTION:The processor 1 outputs the address A, date B having the same contents as the address A, and a control signal to the bus 2. At the digital output device 3, an address decoder 4 sets the address A and decodes it to output one selection signal 4a. Further, an output enabling circuit 5 outputs a write signal 5a to an output latch and a driver 6. A comparator 9 compares the address A to the data B to output a signal 9a when they coincide with each other. By three inputs (4a, 5a, and 9a), each output latch and the driver 6 outputs a process signal corresponding to the selection signal 4a to drive a corresponding electromagnetic relay 8, thereby turning on a pilot lamp 7. Consequently, a high reliable, noise-tolerant system is constituted. |
