Running a DSC Module Application (DSC Module)
June 2008
NI Part Number:
371618D-01
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The Heat Exchanger project, located in the labview\examples\lvdsc\Applications\Heat Exchanger directory, provides a useful example of the process that occurs when you run a LabVIEW Datalogging and Supervisory Control (DSC) Module application. The Heat Exchanger example project simulates the activities of a heat exchanger in which hot air passes through several cooling units and then exits the system as cold air.
The Heat Exchanger example project is organized in a LabVIEW project. The project consists of several folders, a readme, a LabVIEW project library, and the Heat Exchanger VI. The Heat Exchanger Files item in the Project Explorer window contains the support VIs for the project.
When you open and run the Heat Exchanger VI, LabVIEW automatically deploys the Heat Exchanger System 01 project library. This project library contains the shared variables to which the front panel controls are bound. The first time you run the Heat Exchanger VI, small red indicators appear next to the front panel objects. These small red indicators imply that the data items do not exist or the data quality is bad. The connection is unsuccessful because you first must create a custom I/O server for this project.
The IO server folder from the Heat Exchanger example project contains the VI source for the custom I/O server. This VI simulates the activities and value changes in the heat exchanger. When you run the Heat Exchanger - Simulation VI, the values of the front panel indicators update without errors. You can convert this VI into a custom periodic I/O server that you then can use with the Heat Exchanger VI.
The readme_HeatExchanger.rtf file in the Heat Exchanger example project provides instructions for converting the Heat Exchanger - Simulation VI into a custom periodic I/O server. After you build the custom I/O server and run the Heat Exchanger VI again, small green indicators appear next to the front panel objects to indicate a successful connection to the Shared Variable Engine (SVE). The values of the front panel objects also update with the values that the Heat Exchanger - Simulation VI generates.
The following figure illustrates the process that occurs when you run the Heat Exchanger application.
The previous figure illustrates the following process:
- The Heat Exchanger VI runs and deploys the Heat Exchanger System 01 project library, which contains shared variables and the associated custom periodic I/O server, HeatExchangerServer. LabVIEW deploys the project library to the SVE.
- The SVE simulates the heat exchanger using the configuration stored in the project library.
- The SVE passes the output of the heat exchanger simulation to the shared variables in the project library.
- The front panel of the Heat Exchanger VI interacts with the shared variables using front panel data binding. When a user changes the value of a front panel control, LabVIEW sends the updated value back to the SVE.