Scan class health points

Unless otherwise stated in the description of the point, a scan class health point will receive the system digital state No Data if a scan class is defined and a scan class health point for the class is loaded by the interface but there are no interface points loaded for the scan class. For points configured to monitor a particular scan class, the PI point attribute Location4 must be set to a valid scan class. Scan classes are defined with the /f startup parameter. See the list of startup parameters for a description of the /f parameter.

• Scan class IO rate [UI_SCIORATE]

  Shows the health of input points defined for a particular scan class. The point indicates the number of events sent to PI Server before exception processing for the given scan class. As long as the current value of the point is between zero and the scan class point count inclusive, then the scan class update executed successfully.

  If the scan class IO rate point stops updating in PI Server, an error has occurred and the points for that scan class are no longer receiving new data. The value of this point is updated after the completion of each scan.

• Scan class bad value rate [UI_SCBVRATE]

  Calculates the number of values sent to PI Server (before exception processing from the device) with a status other than good. This point can be defined for each scan class and is used for all input points in that particular scan class.

• Scan class scan count [UI_SCSCANCOUNT]

  Tracks the number of scans that were performed by the interface since the last reporting period. The value of this point is incremented after the completion of every scan. The value of the point is set to zero at the beginning of each reporting period.

• Scan class scans skipped [UI_SCSKIPPED]

  Tracks the number of scans not performed before the scan time elapsed and the next scheduled scan executed. The value represents the total number of scans skipped since the last reporting period, and updates each time a scan is skipped. The value is reset to zero at the beginning of each reporting period.

• Scan class point count [UI_SCPOINTCOUNT]

  The number of points loaded by the interface for a particular scan class. The value of this point is updated after every scan. If there are no points loaded by the interface for the associated scan class, 0 will be written to the scan class point count point.

• Scan class scan time [UI_SCINSCANTIME]

  The total amount of elapsed time in milliseconds to read data from the data source, populate the input points, and then send the data to PI Server. The value for this point is updated after each completed scan.

• Scan class input device scan time [UI_SCINDEVSCANTIME]

  The time in milliseconds to read data from the data source and populate input points. The scan class device scan time is a subset of the total scan class scan time and can be used to determine the percentage of time spent communicating to the data source compared with the percentage of time spent communicating with PI Server.

If the scan class skipped point

value is increasing, the scan time points along with the device scan time points can be used to help identify where the delay is occurring; for instance, the data source communication, PI System communication, or elsewhere in the interface control loop.