Abstract: A diagnostic device includes a storage unit that stores first information including a first abnormal event which occurred in the past in a plant, a first attribution event that is a cause of the first abnormal event, and a first occurrence probability of the first attribution event, in which a causal relationship between the first abnormal and attribution events is indicated by a tree structure, and second information including a second abnormal event which is supposed to occur in the plant but has not yet occurred, a second attribution event that is a cause of the second abnormal event, and a second occurrence probability of the second attribution event, in which a causal relationship between the second abnormal and attribution events is indicated by a tree structure; and an estimation unit that estimates the cause of the sign of the abnormality, based on the first and second information.

Abstract: A collection device includes a reception unit, a first inspection unit, and a first transmission request unit. The reception unit receives a data unit including operation data indicating an operation state of a plant and a guarantee value for guaranteeing authenticity of the operation data. The first inspection unit inspects the authenticity of the data unit by inspecting a quality of the data unit on the basis of the guarantee value and by inspecting the presence or absence of a loss of the data on the basis of a reception interval of the data unit. The first transmission request unit requests a transmission side of the data unit to retransmit the data unit when inspection results of the first inspection unit indicate no authenticity.

Abstract: A diagnostic device includes a storage unit that stores first information including a first abnormal event which occurred in the past in a plant, a first attribution event that is a cause of the first abnormal event, and a first occurrence probability of the first attribution event, in which a causal relationship between the first abnormal and attribution events is indicated by a tree structure, and second information including a second abnormal event which is supposed to occur in the plant but does not occur yet, a second attribution event that is a cause of the second abnormal event, and a second occurrence probability of the second attribution event, in which a causal relationship between the second abnormal and attribution events is indicated by a tree structure; and an estimation unit that estimates the cause of the sign of the abnormality, based on the first and second information.