Introduction to PI Connector for CygNet

PI Connector for CygNet provides unidirectional data transfer from CygNet SCADA to the PI System.

Operational overview

PI Connector for CygNet retrieves data from CygNet by discovering the CygNet data model for the Current Value Service (CVS). After configured, the connector performs the following operations to map CygNet assets to endpoints in the PI System (PI points, AF elements, and AF attributes):

• CygNet asset model discovery

• PI System endpoint creation

• Data collection

• Mapping synchronization

CygNet asset model discovery

The connector starts, connects to CygNet, and queries the CygNet FAC and PNT services associated with the CVS. These services are specified during configuration. Modelling occurs in the following order:

1. CygNet Facilities are queried and mapped to the PI System as AF elements.

2. CygNet Points, represented by the Point's Long Point ID, are mapped to the PI System as AF elements and associated with their parent Facility.

3. The CygNet Point Value is mapped to the PI System as a PI Point for data collection.

PI System endpoint creation

As the connector maps the CygNet model, it creates the PI AF database specified in the connector configuration. The connector creates a root node element, creates CygNet Facility based AF elements using the CygNet Point Facility ID attribute, and then populates the AF elements with discovered attributes.

The connector maps each CygNet Point as an AF element under the Facility element. Each CygNet Point element has a PI point for the value that is listed as an attribute along with additional attributes for the CygNet Point.

Note: By default, your system collects the Point and Facility attributes specified in a ConnectorGlobalConfig file, which must be modified to constrain the number of attributes the system queries. See the following section.

• Constrain attributes

  The PI Connector for CynNet ConnectorGlobalConfig file is typically installed at C:\%PIHOME64%\Connectors\CygNet\Configuration. That file includes the following code, which by default queries all PointAttributes and FacilityAttributes, as none are specified between the [ ] brackets for each parameter.

  

  To avoid slowing your system with unnecessary queries, specify the attributes to collect in the ConnectorGlobalConfig file. The following provides an example in which the connector is set to query eleven PointAttributes, and five FacilityAttributes.

  

  See Appendix: Supported attributes for a list of supported attributes. See the Modify advanced features topic for the procedure for modifying the configuration file.

Data collection

After all CygNet Points associated with the selected CVS have been mapped to PI System endpoints, the connector begins sampling the selected CVS and associated VHS for values for each mapped Point. The default mode of sampling for a Point is from the CVS. The sampling rate is specified in the connector configuration.

For Points that require full resolution of data, the connector can be configured to collect this data using the Value History Service (VHS). Specifying UDCs causes all Points with that UDC to be collected from the VHS. VHS collection cannot retrieve old values from CygNet, only those values available once the connector starts data collection.

Note: Collecting large numbers of Points from the VHS can degrade system performance. Only collect the minimum necessary Points from the VHS.

Analog, String, Digital and enumeration CygNet point types are supported.

Mapping synchronization

PI Connector for CygNet periodically checks for new Facilities and Points as they become available. However, the connector only creates the corresponding AF elements and PI points if the UDCs have been added to the list of UDCs to collect. Edits to attributes of existing CygNet Facilities and Points are periodically updated in the PI System.

Note: The connector does not delete any AF elements or PI points created in the PI System. If a CygNet Facility or Point is removed from the data source, "_MarkedForDeletion" is appended to the corresponding AF element name and the PI point stops updating. If the connector is not running when the CygNet Facility or Point is removed from the CygNet system, or the connector is stopped prior to appending “_MarkedForDeletion” to the AF element name, the AF elements will not be marked for deletion when the connector is started again.