| 摘要 |
<p>[Problem] To provide, in a control/monitoring signal transmission system in which data is transmitted in a transmission synchronization scheme, a disconnection detecting scheme by which it is possible on the master side to easily detect whether there is a disconnection at an input signal wire of an input unit that is a three-wire sensor, and also to provide a slave terminal used in this scheme. [Solution] A slave terminal corresponding to an input unit sets a time period during which a load resistance of the input unit is set to be either on or off while the input signal wire of the input unit is properly connected, determines whether the connection state of the input unit is normal or abnormal on the basis of both output logical data from the input unit for when there is an object to be detected and when there is not an object to be detected, where the logical data is obtained during the time period when the load resistance is set to be on, and logical data for the object to be detected corresponding to changes in current consumed internally for operations of the input unit, where the logical data is obtained during the time period when the load resistance is set to be off, and superimposes a signal constituting data indicating that the connection status of the input unit is normal or abnormal onto a management data area of a transmission signal.</p> |
