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Configure OPC Client Instance Dialog Box (DSC Module)

In the Create New I/O Server dialog box, select OPC from the I/O Server Type list and click the Continue button to display this dialog box. You also can display this dialog box by double-clicking the Create and Configure IO Server Express VI, selecting OPC from the I/O Server Type drop-down list, and clicking the Set Attributes button.

Use this dialog box to configure an OPC client instance. After you configure the OPC client instance, you can bind shared variables to OPC Client instance data items.

  • Settings—Use the settings on this tab to configure the OPC client instance update rate, deadband, and reconnect poll rate. Select the OPC server you want to use in the Select an OPC Server list. Then configure the following settings for the specific server.
    • Browse—Specifies if you want to select a computer from a list of computers that use Logos or a computer on the network.
    • Machine—Specifies the name of the computer from which you can select an OPC server. Click the Browse button to navigate to and select the computer. This option is available only when you select Machine in the Browse pull-down list.
    • Registered OPC Server—Displays a list of OPC servers registered on the computer. This option is available only when you select Machine in the Browse pull-down list.
    • Prog ID—Specifies the ID of the OPC server. This option is available only when you select Machine in the Browse pull-down list.
    • Update Rate—Determines the amount of time that passes before the OPC server communicates updated values to the Shared Variable Engine. This value is a requested update rate for the OPC server. The actual update rate returned by the OPC server is greater than or equal to this value. Entering a value of 0 returns the fastest update rate possible from the OPC server. This option is available only when you select Machine in the Browse pull-down list.
    • Deadband—Sets the percent of change within a range that a value from the OPC server must change before the OPC server communicates the value to the Shared Variable Engine.
    • Reconnect Poll Rate—Specifies how often, in seconds, the Shared Variable Engine attempts to connect to an OPC server after losing the connection to the server. Enter a value of 0 if you do not want the Shared Variable Engine to retry the connection.
    • Select an OPC Server—Displays a list of computers on the network from which you can select an OPC server. This option is available only when you select Network in the Browse pull-down list.
  • Advanced—Use the settings on this tab to configure advanced options of the OPC client instance.
    • Server Instance Preference—Specifies the server to which the Shared Variable Engine first attempts to connect.
      • In Process—Specifies that the Shared Variable Engine attempts to connect first to the In Process server, which is typically a .dll. If the Shared Variable Engine fails to make a connection, the Shared Variable Engine attempts to connect to the Out of Process server.
      • Out of Process—Specifies that the Shared Variable Engine attempts to connect first to the Out of Process server, which is typically an executable (.exe file). If the Shared Variable Engine fails to make a connection, the Shared Variable Engine attempts to contact the In Process server.
    • Read/Write Method—Specifies how the Shared Variable Engine waits for the OPC server.
      • Asynchronous—Specifies that the Shared Variable Engine does not wait for the OPC server to process the write operation before continuing.
      • Synchronous—Specifies that the Shared Variable Engine waits for the OPC server to process the write operation before continuing. As a result, the Synchronous option can cause slow response times and poor system performance.

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