Edit general information for a topic

To edit general topic information

1. In the Operations Control Management Console tree, expand a server group and then expand a server.

2. Expand Configuration Editor, expand System Configuration, and then expand Data Acquisition.

3. Expand the IDAS and then the I/O Server that contains the topic to edit.

4. Right-click the topic, and then click Properties. The Properties dialog box appears.

   

5. In the Topic Name list, type the name of the topic.

6. In the Time Out box, enter 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. The default is 60000 milliseconds.

   Note: You can also manually force a reconnect for one or all of the topics in the system. For more information, see Reinitialize I/O topics.

7. To disable the time out, mark the Set to No Time Out check box.

   You might want to disable the time out if the topic has data values that are not changing at all or changing very slowly. If you have a slow-changing tag for which a time out is occurring frequently, you will see periods of NULL data in history, as a result of the Historian disconnecting and reconnecting. Disabling the time out prevents the Historian from disconnecting, so that valid data is always being logged.

   The topic timeout is automatically set to 0 and disabled if you enable late data for the topic (configurable on the Set Storage Rules tab).

   To allow acquisition of "late" data, mark the Enable Late Data check box.

8. If you are configuring a topic for a classic IDAS (that is, an IDAS that existed before installing Historian 2017), configure these options:

   

   • For Idle Duration, specify 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.

   • For Processing Interval, specify 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.

9. Click OK.