Use the search and browse feature to view Kepware's repository of more than 500 Knowledge Base articles. Narrow your results or type your query into the search field below.

Search Solutions Results By: View All Solutions

Kepware Knowledge Base: Solution


All Tags in a Group Remain Bad (Out of Service)


Last Update: 11/7/2018

The default setting for OPC DA compliance is "Return initial updates for items in a single callback". This means that until a device gets initial values for all tags in a group, none of the tags will be updated. Delaying the initial update until all tags have a value avoids issues that can occur when logging data on data change (or when client applications are using trends or alarms). For example, an initial update with unknown values and bad quality can cause bad data to be logged, erroneous alarms to be triggered, and invalid trends.

In some cases, this behavior can cause groups that contain unsolicited tags to remain "Bad (Out of Service)" for an extended period of time. Projects with large quantities of tags using a non-blocking protocol can also exhibit this behavior because it can take a long time to read all the tags.

Solution:

  1. Once initial updates have been received for all tags, the tags will begin updating normally. If unsolicited update rates are known to arrive in a fixed period of time and data collection is not required to start immediately, wait until all unsolicited data arrives. For example, if unsolicited tags are known to update once every five minutes, wait five minutes. After this period of time, all tags should have received initial updates and will begin updating normally.
  2. Configure unsolicited tags and solicited tags into separate groups. Doing so will enable the solicited tags to begin updating immediately; the unsolicited group will remain "Bad (Out of Service)" until all unsolicited tags in the group have received their initial updates.
  3. Configure tags to start updating individually. To do so, open Project Properties and select the OPC DA Compliance tab. Then, uncheck the Return initial updates for items in a single callback setting. Individual tags will remain "Bad (Out of Service)" until they receive an update from the device.
Related Products
KEPServerEX