DeltaV Diagnostics and the Continuous Historian subsystem

Only top-level diagnostic information about the health and performance of the Continuous Historian subsystem is available as diagnostic parameters and visible in DeltaV Diagnostics. Diagnostic parameters expose status Booleans or numeric levels that give you a way to use custom alarm logic to draw more attention to problems in the historian.

Note

The Continuous Historian subsystem exposed in DeltaV Diagnostics depends on which historian is installed, as follows:

Diagnostic parameters for the CHIST subsystem are listed for a workstation where the DeltaV Continuous Historian is installed while DeltaV services are running.
Some diagnostic parameters for the CHIST subsystem are also listed when the Advanced Continuous Historian or OSIsoft PI Server is installed on an Application Station, as indicated in the footnotes for the following table.

The Continuous Historian subsystem exposes the following parameters:

Name	Type	Description
BadRead⁽¹⁾	Int32	Number of history collection tags that should be on scan but cannot be read for data sampling.
BadWrite⁽¹⁾	Int32	Number of history collection tags that should be on scan but cannot be written to historical data storage. If greater than 0, forces OINTEG to 1 (BAD).
DCLoad⁽²⁾	Float32	Data collection loading factor. Percent of time available for scanning used for scanning. For example, 20 indicates that scanning took 20% of the time available to the scanning process. Greater than 100 indicates that scanning is not keeping up with the configured scan rates.
DCStop⁽²⁾	Boolean	0 = NO, 1 = YES. The string value is displayed in Diagnostics. YES, if real-time data collection has been stopped due to: Data storage database could not be opened for writing Data storage disk has too little free space for normal operation If YES, forces OINTEG to 1 (BAD).
ErlActive⁽²⁾	Int32	Number of early active historical data set creations since DeltaV software and the DeltaV Continuous Historian were started. The number of times that the current historical data set created was size-limited rather than corresponding to the desired time period.
Exist⁽¹⁾	Boolean	1 if the DeltaV Continuous Historian is installed on this workstation; otherwise, reports a read error.
ExpFails⁽²⁾	Int32	Number of failed attempts to export a historical data set since DeltaV software and the DeltaV Continuous Historian were started. Remains 0 if no Automatic Export directory is configured.
HistRev⁽³⁾	String	Indicates the revision level of the continuous historian software.
HsLoad⁽²⁾	Float32	Historical data storage process loading factor. Percent of time used in each historical data storage cycle. For example, 20 indicates that, in the last historical data storage, 20% of the time was used, and 80% of the time was waiting for the next storage cycle. Greater than 100 indicates that the historical data server’s memory data cache is filling because storage is not keeping up with the scanning interface.
HsWrites⁽²⁾	Int32	Number of samples written to historical data storage during the last storage cycle.
Items⁽¹⁾	Int32	Number of history collection tags currently configured.
ItemPSec⁽¹⁾	Int32	Number of history collection tags currently being scanned per second.
Load⁽³⁾	Float32	The current loading status of the scan system as a percentage, from 0 to 100 percent. For example, a value of 1.1 indicates that the scan system is 1.1% loaded.
LongRead⁽²⁾	Int32	Number of long outstanding reads that could be causing a loading problem on the server but are not included in the SAMPREAD value. If 0, no reads are in progress. In this case, a non-incremental SAMPREAD value indicates that no read activity has occurred in the last reporting period. If greater than zero, at least one, possibly significant read is in progress. In this case, the LONGREAD value indicates the duration for the longest read in progress. The duration indicates the significance of the read.
NumClient⁽²⁾	Int32	Number of clients connected to the historical data server.
OInteg⁽¹⁾	Boolean	Composite integrity of the DeltaV Continuous Historian data collection and historical data server. 0 = GOOD , 1 = BAD. The string value is displayed in Diagnostics.
OnScan⁽¹⁾	Int32	Number of history collection tags currently configured that are on scan; excludes items that are disabled or cannot be read or stored to historical database.
PriUtil⁽²⁾	Float32	Primary storage utilization factor. Percent of the Primary storage target size that is currently consumed by active and current historical data sets.
PriXsMb⁽²⁾	Int32	Excess disk space in MB (1,048,576 bytes) currently on the Primary storage drive if the Primary storage area reached the configured size target. Computed as: `available disk space on the Primary storage drive` – `Primary storage size target` + `Primary storage used` This value becomes negative if there is insufficient storage on the Primary storage drive for the Primary storage area to reach its configured maximum size target; that is, if disk space is likely to run out, which will cause history collection to stop. If less than 0, forces OINTEG to 1 (BAD).
ReadPSec⁽²⁾	Int32	Number of history samples sent to historical data storage per second. When compression is enabled, only samples for parameters that have changed are sent to historical data storage. When compression is disabled, a sample is sent each scan cycle regardless of a parameter change being detected.
SampRead⁽²⁾	Int32	An incremental count of all the data samples read since the historical data server started. This count does not include reads in progress. Under normal operating conditions, the historical data server updates its diagnostic information every 30 seconds.
ScanChks⁽²⁾	Int32	Items scanned activity counter, displaying in Diagnostics the number of times since the DeltaV system has been started or restarted that it checks a history tag for a new value. As long as one or more history tags are configured for data collection, this parameter increases until it reaches its maximum value, 2³², and rolls over to zero.
SCTORec⁽²⁾	Int32	Scanner connection timeout recoveries, displaying in Diagnostics the number of times since the DeltaV system has been started or restarted that the scanning interface has recovered from a connection timeout. These timeouts tend to occur on workstations that are extremely overloaded with interactive activities for many seconds at a time.
Server⁽¹⁾	Boolean	Historical data server is available. 0 = NO (not available), 1 = YES (available). Forces OINTEG to 1 (BAD) if SERVER is equal to 0 and ITEMS is greater than 0.
SiLoad⁽²⁾	Float32	Scanning interface loading factor. Percent of time used in each scanning interface data transfer. For example, 20 indicates that the scanned data transfer took 20% of the cycle time, and 80% of the time was waiting for the next transfer cycle. Greater than 100 indicates that the scanner process in memory data cache is filling because the scanning interface is not keeping up with scanning.
SiWrites⁽²⁾	Int32	Number of samples transferred by the scanning interface during the last transfer cycle.
SwRev⁽¹⁾	String	The DeltaV software revision number.

⁽¹⁾ DeltaV Continuous Historian, Advanced Continuous Historian, and PI Server

⁽²⁾ DeltaV Continuous Historian only

⁽³⁾ Advanced Continuous Historian and PI Server