DataHub Registry Entries

Controls the polling for network computer names. By default a DataHub instance will poll the network periodically for the Windows names of all computers. This may cause unwanted network traffic. Setting this value will have the following effect:

Numbers < 0 are treated as 0. Numbers between 2 and 1000 are treated as 1000. If the key is absent then the DataHub instance defaults to 10,000ms.

Cause the Event Log to be emitted to the debugger console. This is only useful if the DataHub instance is running within a debugger (Visual Studio or WinDbg).

Cause debug-level messages to be emitted to the debugger console. This will only take effect if EmitConsoleEvents is also enabled.

The DataHub instance maintains an internal data domain called “Status” that contains information about its state. This domain is normally not visible in the data viewer, nor visible in queries of available data domains. This value will make the Status domain visible.

Sets the operating system thread priority for the main DataHub thread.

Sets the maximum timer resolution in milliseconds. The DataHub instance will adjust the system “multimedia timer” to this resolution. If this value does not exist then the DataHub instance will query the operating system for the highest available resolution and use that. This number must be at least 1.

Enables multimedia timer adjustment. If this value exists and is not zero then the DataHub instance will adjust the system-wide multimedia timer resolution to the value described in TimerResolution.

The default is 1.

Allow the DataHub instance to process a DDE Advise message while another DDE message is being processed. This is generally dangerous, as the DDE protocol can become confused over which messages belong to a specific transaction. Enabling this could result in failed DDE transactions.

The default is 0.

Force the DataHub instance to use a specific SSL method. If this registry entry does not exist then the DataHub instance will use the best available method. Can be one of:

The font size of the Event Log window.

Event Log display technology selection. This can be one of:

The name of the font to use in the Event Log window.

A DataHub instance waits for 30 seconds after a client connects before verifying the client's license. If the client does not transmit licensing information within the 30 second window, the DataHub instance will assume that the connection is from a custom application using a direct TCP connection, and will attempt to assign a TCP Link license to that client. If no TCP Link license is available, the DataHub instance will terminate the connection with a "no license" error.

You can modify this licensing window up to 60 seconds by creating this DWORD registry entry.

If you are attempting to tunnel data on a very slow network, it is possible that the slave (client) the DataHub instance sends its licensing information within the 30 second window, but the master DataHub instance does not receive it in time. In this case the DataHub instance will report a no license error even though both the slave and master are correctly configured with tunnelling licenses. If you encounter this case, try increasing the license window to 60 seconds, or improve the performance of the network.

Older versions of the DataHub program set this licensing window to 5 seconds, and did not read the registry entry. If you are encountering issues with a 5-second licensing timeout, please upgrade at least the master DataHub instance to a more recent version.

The number of bytes of output that a TCP socket can buffer before the socket is considered “hung” as is closed. The default is 50,000,000.

The number of bytes of output that a TCP socket can buffer before the socket starts refusing new data point updates. This is a throttling mechanism that results in old data point values being dropped when newer values for the same data point become available. When the socket buffer is cleared then the DataHub instance automatically stops throttling. The default is 200,000.

The default is 0.

Force the OPC DA Classic item browser to use a specific technology (OPC DA2 or DA3). If this value does not exist then browsing will use the selected technology from the OPC client configuration dialog.

Normally the DataHub instance will set its OPC DA client group name to the program name. If this registry entry exists then this value will be used as the OPC DA client group name instead.

This entry tells the DataHub instance to append a sequence number to the OPC client group name. This can be useful if you are tracking an issue with repeated DCOM disconnections.

This entry sets the current sequence number for the OPC client group. It persists through starts and stops of the DataHub instance.

This entry enables an additional memory check for some OPC DA operations. This option increases CPU usage substantially, so only use this if you suspect an OPC-related memory problem.

This entry will instruct all OPC A&E client (outbound) connections to ignore condition attributes. This can save memory when there are a large number of conditions with attributes.