The mapping source is a data provider and/or consumer external to your application code.

For OPC Data Access, there are two types of mapping sources that you can use:

• The DAClientItemSource represents an OPC item.
• The DAClientPropertySource represents an OPC property.

For OPC Unified Architecture, following type of mapping source exists:

• The UAClientDataMappingSource represents an attribute of an OPC-UA node.

One mapping source can be (and often is) shared by multiple mappings. This happens e.g. when you map multiple members to the same source, using different Mapping Kinds (for example, you may map separate members to the value, timestamp, and quality information of the OPC item).

When you use the attributes to define the live mappings, mapping source objects are created and maintained together with their Mappings, so normally you do not deal with them directly.