| 摘要 |
PURPOSE:To enable the fault of fans to be detected without errors by detecting rotation pulse signal of fan bodies, and by directing the output of the selection signal of fans to a selection line, to detect the level of a signal line. CONSTITUTION:By fan bodies U1-Ui, selection signal fed via a selection line L1 is received, and specified fans 11-22 are selected, and pulse according to the rotational frequency is fed back to a rotational frequency detecting means 31. The level of a signal L2 in this case is detected by a level detecting means 33. When the fan bodies U1-Ui are not mounted on, than a connector SC is connected to the signal line L2, and the level of the signal line L2 is set to te a high level or a low level. When the level detecting means 33 detects that the level of the signal line L2 is kept to be the high level or the low level, then a data obtained by the rotational frequency detecting means 31 is neglected. As a result, the fault of the fans 11-22 can be detected without errors. |
