We have noticed a direct correlation to Active Directory (AD/Internal Hybrid) and Tag Quality.
The observation comes from three different servers running two very different projects.
One project (in our Tremonton facility) is polling a single Allen-Bradley tag and doing:
- Oracle database SELECT statements
- Oracle database INSERT statements
The other project (in our Ogden facility) is:
- polling a TCP Proxy Server tag:
a. Parsing an XML message
b. system.opc.writes depending on the content of the XML
c. responding to the TCP Proxy client via system.tag.write
- polling four Allen-Bradley tags and based on tag value changes:
a. system.opc.writeValues and/or system.tag.writeAll
b. structure an XML message
c. system.tag.write to the TCP Proxy client
Turning OFF the configuration setting “List Users from Active Directory” seems to resolve the tag quality problems but still allows us to validate credentials through AD.
It appears that the server loses quality on the tags that are polled when the LDAP query is running and there seems to be no control of when or how frequently the LDAP query runs