| 摘要 |
PROBLEM TO BE SOLVED: To prevent the output of an erroneous signal to external equipment. SOLUTION: An input/output(I/O) unit is provided with output parts 7a-7d connected to the external equipment and capable of outputting electric signals, a control part 2 for controlling the output parts 7a-7d in accordance with an instruction from a CPU unit, an operation power supply part 3 for generating the operation power Vcc of the control part 2, and an insulation circuit part 8 insulating between the control part 2 and the output parts 7a-7d to transmit/receive signals between them. The I/O unit is also provided with a driving power supply part 9 for receiving power supply from the external and generating driving power for the circuit part 8, a reset circuit part 10 for outputting a reset signal and a reset signal transmission part 5 for insulating between the circuit part 10 and the power supply part 9 and inputting the reset signal outputted from the circuit part 10 to the power supply part 9. At the time of starting the supply of operation power from the operation power supply part 3, the supply of driving power to the insulation circuit part 8 is forcedly stopped, so that the output of an error signal to the external equipment can be prevented at the start time or the like causing instability in the operation of the control part 2.
|
