About IDASs

An IDAS (Industrial Data Acquisition Service) accepts data from one or more I/O Servers or other data source and sends it to AVEVA Historian for storage. If the connection to the Historian is not available, IDAS caches the data locally and forwards it later when the server is back online.

Note: IDAS configuration information is stored in the _IODriver table in the Runtime database.

When you add an I/O Server definition to the Historian, a topic object is created in the associated IDAS. A separate topic object exists for each unique combination of I/O Server computer, application, and topic. Each topic object maintains its own state: idle, connecting, connected, disconnecting, disconnected, overloaded, or receiving. Also, each topic object is assigned a data time-out value based on your assessment of how often data changes for that particular topic.

An IDAS can accept data from one or more I/O Servers but sends data only to a single Historian.

An IDAS can run on the same physical computer as the Historian, or on a remote computer. Use the Ping command to check the availability of the remote IDAS or Historian computers.

IDAS seamlessly handles data values, irrespective of their time. For each data point acquired by IDAS, the timestamp, value, and quality are historized in accordance with the storage rules for the tag to which the data value belongs.

For information on configuring an IDAS, see Configure data acquisition.