| 摘要 |
PURPOSE:To diagnose a fault of the hardware logical part of a receiving circuit, by feeding the output data of a transmitting circuit back through the receiving circuit and then comparing the feedback data with transmitted data to the transmitting circuit. CONSTITUTION:A carrier output signal 20 from the terminal CRY of a 4-bit counter 17 is inputted to the terminal A of an 8-bit comparator 22 and at its timing, the serial transmitted data of a shift register 18 is compared with the read-back data of a shift register 19. Therefore, if an intermit error occurs to the transmitting or receiving circuit, the output signal 23 of the comparator 22 goes down to a low level. Then, the output signal 30 of a flip-flop 24 goes up to a high level to turn on a light emitting element 32 through a gate element 31, performing error display. |
