How to use the History Transporter Object
The History Transporter Item is used to transport historical data for selected tags from an external historian to the system:inmation historian. The History Transporter item allows you to control the transport of the data in terms of scheduled cycles to effectively transfer large amounts of historical data without over-straining the system or the respective historians.
The History Transporter is part of the History Transfer Chain suite of objects that enable multiple options to transfer data between different external historians, export data to file or to import data into system:inmation. For an overview and examples of using the History Transporter with the other History Transfer Chain objects please visit the Using History Transfer Objects Jumpstart section of the documentation.
The following example will show you on example of using the History Transporter on its own, however, it is generally better to configure the Transporter object using a History Controller as described in the Using History Transfer Objects Jumpstart. This allows more flexibility to change configurations and add more History Transfer objects in the future.
|For this example we will connect to an inmation OPC Server instance (that has OPC HDA capabilities) and transfer historical data from the DemoData items (Massconfig sheet to create these items can be downloaded here). The data is transferred from the inmation historian however, this will also work using any other Datasource with OPC HDA capabilities that is connected to an external historian. If you cannot see the inmation Server under your Connector object you may need to remove it from the discovery blacklist found in the Connector properties under Connector Options > Datasource Blacklist in the object properties panel.|
To create a History Transporter item, select the Datasource object, right-click and selectFigure 1. Adding a History Transporter Item
In the Create Object wizard, give the History Transporter a name and click Create.
Select the History Transporter in the I/O model and in the Object Properties panel click on the Tag Configuration table icon to open the tag configuration table.
The Tag Configuration Table property is where you select the I/O items from which you want to transport the historical data. The table has 6 columns:
External ID: the External IDs of the items from which the historical data will transferred
Aggregate: the required aggregate for the data (only Raw History currently supported)
NodeName: node that will be created under the History Transporter for new objects
ObjectName: the name of the object that the historical data will be transferred to
Expected Frequency: the expected frequency of the time points in the external historian (e.g. 5s would be every 5 seconds)
Target ID: the unique identifier in the destination historian system in case the item is used with a history sink function
The ExternalID and ObjectName columns are mandatory.
|To fill out the tag configuration table you need to use the external ID of the target items, this can be found in the object properties panel under the Item ID property. For an OPC Classic I/O item this could be something like Random.Int1. In this example, we are using the DemoData examples found under the inmation Server, browse the server to find the objects are retrieve the external IDs from the object properties panel.|
Select objects and copy their Item IDs into the ExternalID column of the tag configuration table. The History Transporter will create new I/O item beneath itself to which it will transport the history data.
In the NodeName column you can enter a folder name if you want to separate these items into separate nodes.
The new I/O items will be created with the name given in the ObjectName column. Click Apply to save the Tag Configuration table.
|At the moment the History Transporter can only transport Raw History but in the future other aggregates will be available.|
The schedule for the History Transporter to transfer the history data is configured in the Object Properties panel. There are two modes, Simple and Scheduler. The simple mode will transfer data on a by minute, by hour, by day schedule until all history data for the configured time period is transferred. The scheduler mode allows you to link the History Transporter to a Time Scheduler item so the history transfer will proceed at very specific times.
For the purpose of this example we will use the simple schedule mode and set it to happen every minute. Click Apply to save the changes.
The time period for history retrieval is configured using the Depth property. A relative time period from the current time backwards can be configured, for example to transfer the last 100 days of history *-100days can be set.
The Slicing property determines what percentage of the alloted schedule time will be used for the history transfer. This is important to limit the amount of data transfer on the network and the relative historians that are being queried and subsequently written to (the max Slicing setting is 75%).
The amount of data transfer can also be controlled using the Hedging property. This will limit the number of data points that can be transferred in the scheduled time period (max Hedging value is one million points). The hedging value will overrule the slicing setting when reached.
The History Transporter has 4 Processing Modes:
The Configuration mode (default when object is created) allows you to configure the item and all the settings before commencing the History transport. It is normally leave it in this mode until we wish to begin retrieving the historical data.
The Subscription mode will begin the history transfer by creating new items beneath the History Transporter object (according to the Configuration table), create a subscription to the original items to receive new updated values, and then begin transferring the history data on the set schedule.
The Continuous mode will create the new items and begin transferring the history data. No subscription is made so history calls to retrieve the values from the external historian up to the point the mode was applied.
The Reset mode is used to reset the whole history transport process if you want to begin again. This mode will automatically set the processing mode back to Configuration after the reset.
For this example we will use the Subscription mode so choose this from the dropdown menu and click on Apply.
Once the processing mode is selected and applied, the State Management section of the object properties panel indicates how long remains until the next transfer cycle. If the simple schedule mode is chosen then the transfer will begin on the minute, hour or day depending on what time was chosen.
Once the time has counted down, the History transporter creates the items beneath itself (including any selected nodes) and begins transfer. The status of this can be followed in the state management and diagnostics section of the properties panel.
Opening the State Table shows you all the selected items and the progress of the history transfer including any remaining backlog and the number of data points transferred.
Once the history transfer is completed for each item, the state table will indicate this in the State column.
|If there is any problem with the transfer or the configuration, an error message will be displayed in the Error column of the State Table. Error messages are often given if the ExternalID was entered incorrectly in the Configuration table so it is worth double checking this if you encounter any problems.|