DETECTING SYSTEM OF COMMAND FAULT

摘要

PURPOSE:To detect the fault of a command with a simple circuit constitution and a simple control regardless of the bit length of a command, by using a simple counter circuit to detect the fault of a command of a receiving device. CONSTITUTION:A command sent from a command transmitting device is received by a command receiving device 31 via a data bus DB. A signal S2 is sent to a counter circuit 33 as soon as the circuit 31 receives the command. Thus the circuit 33 is actuated. At the same time, the received command information S1 is supplied to a command analyzing/executing circuit 32. Then a command execution end signal S3 is supplied to the circuit 33 as a reset signal when the execution of command is through with the circuit 32. When the circuit 32 receives a command in a normal way, the circuit 33 is reset with the signal S3 before an overflow time. Then an overflow is produced from the circuit 33 when an abnormal command is received, and a command fault detection signal S4 is delivered.