Access to remote historical objects ("historical gateway mode")

The D2000 GateWay Client process can also be configured to access remote historical objects. In this mode, it masquerades as an archive (i.e. process SOME_NAME.ARC). It receives from the D2000 Server a list of historical objects for which it is the parent and tries to verify whether the required historical objects exist in the source system and, if so, ensures the transfer of the values of these objects (if the historical objects publish their values).
Note: if it is necessary to transfer the published values of structured historical objects, which are published to the columns of structured variables, this functionality is not handled by the historical mode - use either the standard gateway mode with remote objects or the transparent gateway mode with the transfer of the values of the entire structured variables.

Therefore, it is necessary to create a new archive process in the destination system (e.g. REMOTE.ARC) and import the definitions of the required historical objects from the source system, changing their parent to this new archive process. Subsequently, the D2000 GateWay Client must be started in historical mode.

At the same time, the D2000 GateWay Client implements reading values of historical objects into graphs and handles the following actions in the script:

• CALCSTATFUNC
• CALCSTATFUNCARR
• GETARCHARR
• GETARCHARR_TO_CNT
• GETARCHCOL
• GETARCHROW
• GETARCHSTRUCT
• GETARCHVAL

No values are transferred from the destination system to the source system, and deletion and on-demand recalculation of calculated/statistical historical objects are not allowed. The value transfer is always unidirectional, so the gateway works as a Data Diode.

Therefore, the following actions are not supported:

• editing archive value in D2000 HI
• CALCONDEMANDSTAT
• DELETEARCHDATA
• INSERTARCHARR
• UPDATEARCHVAL

The CALCARCHEXPR action is also not supported.

It is not possible to operate the GateWay Client process at the same time in the standard remote tags mode and also in "historic gateway mode", since in standard mode the process has the suffix GTW and is the parent of remote tags, and in the historical mode it has the suffix ARC and is the parent of historical objects.

The GateWay Client process can be, however, operated at the same time in the transparent gateway mode and "historical gateway mode" configurations.

Use of "historical gateway mode"

The historical mode of the gateway is a solution in cases when:

• It is necessary to access the values of the historical objects in the remote system/systems, while it is not desirable to archive them locally (e.g. there is a large number of objects, or not enough disk capacity/memory/power is available for archiving).
• There are script-filled historical objects, for which it would be necessary to duplicate the data-filling mechanism on the target system as well.
• In a test environment, it is necessary to make available (for reading) complete historical data from the production environment (e.g. including data from the depositories, which do not have to be configured on the test environment).

Start parameters

To activate the historical mode of the gateway, start the GateWay Client with /ARC parameter.

An example of running: The GateWay Client will connect to the target system as REMOTE.ARC process and communicate with the GateWay Server listening on address 172.16.0.22 and port 1000.

gtwcli.exe /ARC /WREMOTE /GTWC172.16.0.22:1000

Changing object names

As in the transparent gateway mode, If it is necessary to change object names (i.e. on the GateWay Client side, D2000 objects are named differently than on the GateWay Server side), it is possible to start the GateWay Client process with one or more /MON  (Modify Object Names) parameters.

Syntax: /MON<expression,replacement>

Example: Deleting the string "MPPS." in the names of the opened objects we achieve by specifying /MONMPPS\.,
Example: Replacement MPPS -> MES is achieved with the parameter /MONMPPS,MES

Note: at most one substitution is performed on the D2000 object name (expression is searched for from the beginning of the name). For example, if an I/O tag M.MPPS.test.MPPS exists, then the parameter /MONMPPS,MES causes the  I/O tag M.MES.test.MPPS to be opened on the remote side.

Pairing objects by UID

Historical mode of the gateway, similar to the transparent gateway mode supports pairing not only by object names but also by UID objects. This feature is enabled by the start parameter /UID, which must be used when starting both the GateWay Client and GateWay Server processes.
This feature can be used to implement the functionality of a gateway regardless of changes in the names of the objects (provided that they have the same UID), i.e. objects can be renamed.

Diagnostic information

To activate the detailed debug information, start the GateWay Client with these parameters:

This listing of debug information can be enabled /disabled also while running the GateWay Client through the D2000 System Console.