Communication Failures

Failed Communication with Data Source

OI Gateway behaves in the following manner in the case of failed communication with a data source:

• The gateway attempts to periodically reestablish a connection with the data source up to the maximum number of retry attempts as specified in its Reconnect Attempts parameter.

  Note: The gateway is not responsible for starting the data source server, unless the source protocol supports it. OPC has this capability.

• The gateway marks all items being read from the data source with Bad quality. OPC carries a sub-status of Comm Failure.

• Write attempts to the data source are rejected with an appropriate error code.

Failed Communication with Client

OI Gateway behaves in the following manner in the case of failed communication with a client:

• The gateway unsubscribes (deactivates) all items on the data source that were previously subscribed to by the failed client. (Exceptions: Those items required by other, still connected, clients remain subscribed. Also, in the case of an OPC client, FSGateway maintains subscriptions to all items on the data source previously subscribed to by the failed client.)

• The gateway accepts future attempts to reconnect from the client. Reconnection is the responsibility of the client.

If OI Gateway fails to connect to a remote OPC server through both its ProgID and ClassID, lower the DCOM Authentication Level of the OPC server to None.

To lower the DCOM Authentication Level

1. On the remote computer, open Control Panel.

2. Double-click the Administrative Tools, double-click the Component Services.

3. Expand the hierarchy tree under the Console Root as follows: Component Services, Computers, My Computer and DCOM Config.

4. Click DCOM Config. In the right pane, right-click on the OPC server you cannot connect to, and then click Properties on the shortcut menu.

5. On the General page of the properties dialog box, select None for Authentication Level. Click OK.

Communications failures with an ArchestrA data source behave in the following manner: