Introduction to the PI to PI Interface

The PI to PI Interface copies PI point data from one Data Archive to another. Data is moved in one direction only, from the source to the target PI Data Archive. Typical applications for the interface include the following:

• Isolate users from the source Data Archive to increase security, improve load distribution, or resolve remote access issues.

• Maintain a copy of archive data on a secondary Data Archive, perhaps as a backup.

• Create a test copy of a production Data Archive.

• Aggregate data from many Data Archives in a single Data Archive.

  Note: You can also use the PI to PI interface for data replication in PI collectives, as an alternative to fanning data using buffering. Only use PI to PI for data replication in a PI collective if it is required for your system configuration or security needs.

Interface PI points are created on the target Data Archive. Each interface point is configured to receive either exception (snapshot) or archive data for a unique source point. PI points receive archive or exception data from the source point. Exception data is data that has not yet been subjected to compression. By default, all points in scan class 1 receive exception data. PI points assigned to any other scan class receive archive data.

The interface supports history recovery, which recovers data for time periods when the interface was not running or was unable to collect data. The history recovery period is configurable, and the default is eight hours.

Both source Data Archive-level failover and UniInt phase 2 interface-level failover are supported. When running in source Data Archive-level failover mode, the interface obtains data from one of two available source Data Archives. To ensure that the interface obtains the same data regardless of which source server is active, the source Data Archives must have identical point definitions and data streams for all interface source points. In UniInt failover mode, two copies of the interface are connected to the source Data Archive at the same time. If the primary interface stops collecting data, the backup interface assumes the primary role and continues data collection. Failover maximizes interface data availability on the target Data Archive(s). Source Data Archive-level failover and UniInt Phase 2 interface level failover modes can be run simultaneously.

Note: The value of [PIHOME] variable for the 32-bit interface depends on whether the interface is being installed on a 32-bit operating system (C:\Program Files\PIPC) or a 64-bit operating system (C:\Program Files (x86)\PIPC).

The value of [PIHOME64] variable for a 64-bit interface will be C:\Program Files\PIPC on the 64-bit operating system.

In this documentation [PIHOME] will be used to represent the value for either [PIHOME] or [PIHOME64]. The value of [PIHOME] is the directory which is the common location for PI client applications.

Note: This interface has been built against a UniInt version (4.5.0.59 and later) which now writes all its messages to the local PI Message log.

Please see the document UniInt Interface Message Logging for UniInt 4.5.0.x and later Interfaces in the %PIHOME%\Interfaces\UniInt directory for more details on how to access these messages.