OPC Item Quality

Associated with each OPC item value is an indicator of the quality of that value. This is known as the OPC item quality. The quality of an item is based on point status information from a CIMPLICITY project and the state of communications between the OPC Server and the CIMPLICITY project.

The CIMPLICITY OPC Server supports a subset of quality flags specified in the OPC Foundation Data Access standard. The supported quality statuses and sub-statuses are listed below.

OPC Status

OPC Sub-Status




The quality of the OPC item value is good.


Last Known Value

Communications with CIMPLICITY project have failed. The OPC item value is the last known value.


Comm Failure

Communication with the CIMPLICITY project has failed. The OPC item value is invalid.

More information

CIMPLICITY OPC Server technical notes.