About data Quality dotfields

The .Quality dotfields indicate the quality of data values the last time data was received. The SuiteLink and DDE protocols only send clients (for example, WindowViewer) updated quality when a data change is provided by the I/O Servers. Therefore, you only observe a quality change when a new data value is received. Some I/O Servers can send current data values with updated quality when the quality associated with the data changes.

It might not be possible to directly reference the quality of a server item's value using the SuiteLink and DDE protocols. To do this, the I/O Server must directly support Item.Quality. Without this support, the item fails to go on advisement and the .Quality dotfield value never changes from 0.

The TestProt I/O Server simulator does not directly support Item.Quality. The simulator does not send out new data values when you modify the quality using the Quality menu command.

If you want to observe data quality for an I/O item and the I/O Server does not directly support addressing of Item.Quality, then define an InTouch I/O tag to look at the server item and then monitor the .Quality of the InTouch tag. If you exceed your tag limit, then consider using the IOSetRemoteReferences() function in a script to dynamically adjust the I/O points.

The SuiteLink and DDE protocols do not interpret connection state or other changes in I/O Server status as quality items sent to the client. As a result, an item's quality does not necessarily indicate the current data server status nor the current status of the client-to-server connection. An I/O Server process can stop and the value of the .Quality field does not change. If the communications link is lost, the value of the .Quality field does not necessarily change.

Use DDE or SuiteLink internal status items to monitor the I/O Server connection.