Data Historian

Introduction

The Data Historian stores timestamped data samples taken from:

You can display data from the Data Historian in a Trend Plot:

A trend plot of two tags in the data historian.

You can display data from the Data Historian in a list:

Choosing Which Tags Store Values in the Data Historian

You can configure which tags store values in the Data Historian using the HistoricEnable property. This property can be set separately for each Data Point Tag and each Time Series Tag.

HistoricEnable	Description
False	No data samples from the tag is stored in the Data Historian.
True	Data samples from the tag are stored in the Data Historian.

Note: If you change HistoricEnable from True to False, the existing data samples are retained in the Data Historian.

Data Access Interfaces

Third party applications can access the Data Historian from these interfaces built in to Fernhill SCADA:

OPC UA Server
OPC Classic Server
ODBC Driver (See the following section to see what type of query to use.)

Using SQL to Query the Data Historian

Each Tag stores historical data in a separate named data table. You can reference the named data table from an SQL Command.

To view the names of historical data tables, do the following:

In the Tag Window of the Configuration Tool, select the Database View tab.
Expand the Historian entry.
Double click Historical Data Index.

To find the name of the historical data table for a tag, do the following:

In the Tag Window of the Configuration Tool, select the Tag.
View the HistoricalTable in the Tag Status Report.

You can query a historical named data table directly. For example:

SELECT 
    ValueTime AS "Time Stamp", 
    ROUNDSD( Value, 4 ) AS "Value", 
    QUALITY_TO_STRING( Quality, TRUE ) AS "Quality", 
    LOG_REASON_TO_STRING( LogReason ) AS "Log Reason"
FROM 
    Historic000014
WHERE 
    ValueTime >= Current_Timestamp - Interval '1' Day
ORDER 
    BY ValueTime DESC
FETCH FIRST 250 ROWS ONLY

Historical Data Views

The Data Historian provides a set of views for querying all historical data of a given type:

View Name	Description
HistoricDataViewBOOL	Historical data for Digital Data Point Tags.
HistoricDataViewLREAL	Historical data for Analog Data Point Tags.
HistoricDataViewTIME	Historical data for Time Series Runtime Tag.
HistoricDataViewUDINT	Historical data for Double Word Data Point Tags.
HistoricDataViewUINT	Historical data for Word Data Point Tags.
HistoricDataViewULINT	Historical data for Long Word Data Point Tags and Time Series Counter Tags.
HistoricDataViewWSTRING	Historical data for String Data Point Tags.

You can use an INNER JOIN to query the historical data for a tag from a historical view:

SELECT 
    H.ValueTime AS "Time Stamp", 
    ROUNDSD( H.Value, 4 ) AS "Value", 
    QUALITY_TO_STRING( H.Quality, TRUE ) AS "Quality", 
    LOG_REASON_TO_STRING( H.LogReason ) AS "Log Reason"
FROM 
    HistoricDataViewLREAL AS H INNER JOIN TagDataPoint AS T
    ON T.HistoricDataTable = H.TableName
WHERE 
    T.FullName = 'Example Graphic.Tank Level' AND
    H.ValueTime >= Current_Timestamp - Interval '1' Day
ORDER BY 
    ValueTime DESC

Further Information

Fernhill SCADA Concepts

To learn about other Fernhill SCADA Concepts.

Configuration Tool

To learn about the tool to configure Fernhill SCADA.

Drivers

To learn about the different drivers available in Fernhill SCADA.

Fernhill SCADA Server

To learn about the SCADA Server.

Data Access

To learn about integrating data into third party applications.

Glossary

For the meaning of terms used in Fernhill SCADA.