Accessing a Remote OPC Server Using Lookout

This document describes how to set up a remote OPC server to communicate with NI Lookout.

You can access a remote OPC server from Lookout in one of the following two ways:

1. Access the remote OPC server directly from the client machine
The OPC client asks DCOM to launch the OPC server on a remote machine. The client passes two parameters to DCOM—the remote machine name and the OPC server ID.

2. Redirect a local OPC server (on the client machine) to the remote OPC server
The client asks DCOM to launch the local OPC server. The DCOM configuration then launches the server on a remote computer.

In order to run remote OPC, both machines must be logged onto the same NT domain. Remote OPC assumes an NT server on your net work that defines an NT domain. National Instruments recommends using the same user account for both machines while troubleshooting.

There is not a significant difference between running Windows 9x/Me and NT/2000 on the client computer. However, there is a significant difference on the server side. While OPC servers on the NT/2000 machines can be launched remotely by the first client, Windows 9x/Me does not have this capability. The server already must be running before the remote client tries to connect. OPC servers cannot be launched manually in most cases. You first must start the OPC server from a local client. You then can connect to the server from a remote machine. NI recommends that you use Windows NT/2000 on the server side.

Setting Up the Remote OPC Communication

You first must configure the remote OPC server using one of the following procedures:
Remote OPC Server on Windows NT/2000
Remote OPC Server on Windows 95/98/Me

You now can configure the OPC client. Complete the following steps on the client computer to configure the OPC client.

1. Select Object»Object Explorer in Lookout to open the Object Explorer window.
2. Right-click the process and select New object from the shortcut menu.
3. Select the OPCClient object.
4. Click the OK button to display the Create OPC Client dialog box.
5. Enter a name for the client object.
6. In the OPC Server Settings:

• If you are directly accessing the remote OPC server:

a) Click the pull-down menu by Server Name to view a list of all the OPC server applications installed on the client computer. Select the server you want to launch from the pull-down menu. If you want to launch an OPC server application that is installed on the server computer but not on the client computer, you must manually type in the OPC server name in the Server Name textbox.
b) Place a checkmark in the Remote server checkbox.
c) Type the name of the computer that contains the remote OPC server in the Remote server textbox. You also can browse the network to find the computer name.

• If you are redirecting the local OPC server to the remote OPC server:

a) Click the pull-down menu by Server Name to view a list of all the OPC server applications installed on the client computer. Select the server you want to launch from the pull-down menu.
b) Place a checkmark in the Local Server checkbox.
7. Click the OK button to create the OPC client object.

See Also:
Setting Proper Access for Remote OPC Server When Using National Instruments OPC Clients

Notes for NI OPC Servers

• Lookout Protocol Drivers - Exit the Lookout Protocol drivers after you configure the drivers. If you do not exit, the OPC server cannot launch.
• FieldPoint OPC Server - Make sure you have a valid configuration loaded in FieldPoint Explorer. You can leave FieldPoint Explorer open when the OPC server is being launched.
• DAQ OPC Server - Make sure you configure the virtual channels in Measurement & Automation Explorer (MAX). You can leave MAX open when the OPC server is being launched.

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