| 摘要 |
PURPOSE:To prevent a master station from malfunctioning owing to a noise, etc., appearing on a bus by stopping the detecting function of a terminal device which detects control information on the bus while the terminal device transfers data as a master station. CONSTITUTION:A CPU 6 resets the inhibit flag of a control register 10 through an internal bus and then generation start control information and then the CPU sets the inhibit flag of the control register 10 after obtaining the control right of the external bus by the generation of the start control information. A gate circuit 20 is therefore closed and the detection outputs of a bus busy detection part 15 and a control right losing detection part 16 are inhibited from being supplied to a status control register 7, so that the system is not controlled by control information on the external bus. Consequently, the system is prevented from malfunctioning a noise, etc., appearing on the external bus and the normal operation of the system can be secured.
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