AppendixA.Command Line Options

For more control of the OPC DataHub on startup, you can use its command line options. These options let you specify data domains, ports, and several other configuration items each time the DataHub starts. Except where noted, these options apply to Cascade DataHub in Windows, Linux, or QNX, as well as Cascade Connect. You need to enter these options in the Properties section of the DataHub shortcut icon.

  1. Right click on the DataHub shortcut icon and select Properties. The OPC DataHub Properties window will appear, with the Shortcut tab selected:
  2. Enter the options in the Target field, after the quotation marks, as illustrated above. The available options are as follows:

    Transmit all point messages to all registered clients, even if the value does not change.

    -b size

    The maximum message buffer size.

    -d domain

    The domain name for this DataHub. This option can be used multiple times to get multiple domains on a single DataHub.


    Do not detach from the controlling tty. Normally the DataHub will detach itself and become immune to interrupts and termination on the controlling tty. If this option is used, then an & is necessary to run datahub in the background.

    -f file

    Load this configuration file.


    Print a help message showing a summary of all these arguments.

    -H home_path

    The full path to the directory that will contain the configuration and license files. This takes precedence over -U. If the directory cannot be found or created, the files will be stored in the installation directory.

    -l file

    Log messages to this file.

    -m port

    Acting as a TCP slave, attach to a TCP master on this port or service. The port is the matching port number of the master, usually 4600;

    -M address

    Acting as a TCP slave, attach to a TCP master on this host. The address is a machine name, such as or a machine address, such as

    -n domain

    Acting as a TCP slave, tunnel this domain from the TCP master. The named domain on the master will be tunnelled to a domain of the same name in the slave.

    -p port

    Act as a TCP master and listen on this port/service.

    -q queue

    Specify an alternate queue name for this DataHub. Normally datahub chooses its own queue name to be unique on the network.


    Synchronized: The DataHub will ignore changes to a point if the point's current timestamp is more recent.


    Automatically generate a timestamp on unstamped points.


    The DataHub should NOT create a directory within the user's personal Application Data directory to store the configuration and license files, but rather in the application installation directory. This has a lower precedence than -H.


    Generate copious debugging information to the standard output. (Implies use of -D).


    Print the version number.


    Exit immediately (usually used with -V).

  3. Click OK and restart the OPC DataHub. The options you have chosen should take effect. Keep in mind that if your configuration file has different values for these options, it will override what you have entered here.