Reference Library for Current Value Table (CVT) Access Centralized Data from Independent Application Sectors

  • Easily share a centralized data component among multiple independent processes
  • Store and retrieve the most up-to-date data asynchronously from various application segments
  • Choose from three sets of API functions that vary in flexibility, performance, and ease of use
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Machine control, automation, and application monitoring are typically all developed as independent processes running on one or more systems. Each process performs a distinct task but shares a set of common data or variables that allow successful completion of all application tasks.

As the central data component, you can use the Current Value Table (CVT) in a wide range of applications. It allows application components to share a common data repository and have direct access to the most up-to-date value of any variable used between components. Using this architecture, one component in the application can handle all of the I/O operations, for example, and share the I/O data variables or tags with other application components. Application operations such as alarm detection, user interface updates, process logic, and so on can then be handled by separate processes sharing the same data repository.

The CVT implementation is a two-layer hierarchy consisting of core VIs and API VIs. The core contains all the functionality of the CVT, including the data storage mechanism and additional service functions. The API VIs provide access to the CVT functionality. You can choose from three groups of API functions that each offer slightly different access to the CVT and vary in flexibility, performance, and ease of use.

System Requirements
Application Software: NI LabVIEW Full Development System 8.2 or later

Disclaimer: This reference architecture was created by the NI Systems Engineering group and is provided as is. NI does not guarantee the performance of this reference architecture. Links to detailed information on this reference architecture and to a forum to provide feedback and ask questions are included in the Resources tab.