_Topic

(PK)
TopicKey

int, NOT NULL

The unique numerical identifier for the topic. This value is automatically generated by the system when the topic is added.

(PK) (FK)
IOServerKey

int, NOT NULL

The unique numerical identifier for the I/O Server. IOServerKey is a foreign key from the IOServer table.

Name

nvarchar(180), NOT NULL

The name of the topic.

TimeOut

int NOT NULL

The time span, in milliseconds, in which a data point must be received on the topic. If no data point is received in this time span, the topic is considered "dead." The historian disconnects and then attempts to reconnect to the topic.

Status

tinyint, NULL

Automatically updated by the system if a change is made to the topic: 0 = No change; 1 = Insertion; 2 = Modification; 3 = Deletion.

LateData

bit, NOT NULL

Used to enable acquisition of "late" data. 0 = Late data disabled; 1 = Late data enabled.

IdleDuration

int, NOT NULL

The amount of time, in seconds, before data is processed from the I/O Server. For example, if you set this value to 60 seconds, data from this I/O Server is cached and only processed by the storage engine after no more data has been received from the I/O Server for at least 60 seconds.

ProcessingInterval

int, NOT NULL

The amount of time, in seconds, after which late data from the I/O Server is processed, regardless of the idle duration. If the nature of the data is such that the idle duration is never satisfied, the historian storage engine processes data from the topic at least one time every processing interval. The processing interval defaults to twice the idle duration and cannot be set to a value less than the idle duration.