Use custom I/O servers when you have a uniquely configured or custom device that you want to use with the LabVIEW Datalogging and Supervisory Control (DSC) Module. Use a custom I/O server to simulate hardware or connect the DSC Module to hardware for which no device server exists. You create custom I/O servers with LabVIEW, unlike OPC servers, which are typically written in Microsoft Visual Basic or C++. A custom I/O server publishes selected data items as NI Publish-Subscribe Protocol data items on the network. The custom I/O server shares ownership of the data with the Shared Variable Engine (SVE), which publishes the data.
For example, you might want to create a custom I/O server in the following situations:
You can create two types of custom I/O servers: on input change I/O servers and periodic I/O servers. Create an on input change I/O server if you want the custom I/O server to update based on an event, such as a change in the value of the input of the server data item. Create a periodic I/O server when you want to control the update rate of a data item and when you want a continuous update of the data item.
The DSC Module provides two wizards to help you create custom I/O servers. Use the Custom VI-based Server – On Input Change Wizard to create an on input change I/O server. Use the Custom VI-based Server – Periodic Wizard to create a periodic I/O server.
To create a custom I/O server, right-click My Computer or a LabVIEW project library or in the Project Explorer window and select New»I/O Server from the shortcut menu. In the Create New I/O Server dialog box, you can select Custom VI - On Input Change or Custom VI - Periodic.