CVT Client Communication (CCC) Reference Library

[Christian_L]

In distributed applications using the Current Value Table (CVT) there is a fundamental need to pass CVT data between targets. This document describes one method of communication between CVT instances on different targets using a TCP/IP client/server protocol.

Description

The primary function of the client communication interface is to share information between CVT instances on the server and the client.  This is done by mirroring portions of the CVT from one side to the other and vice versa.  Generally speaking, there will be certain tags on the server that the client has an interest in.  By the same token, there will be information on the client that needs to be passed down to the server.  For example, if we want to control temperature, then the client needs to send setpoints to the server and then monitor the temperature readings returned by the server.

In applications involving hundreds or perhaps thousands of tags, the importance of efficient communication becomes obvious.  TCP/IP is a standard protocol that is relatively simple yet it offers high throughput and scales well for high-channel-count systems.

Additional Documentation

• CVT Client Communication (CCC) Reference Library

Compatibility and Requirements

• LabVIEW 2010 or later

Dependencies

• NI Current Value Table >= 3.3.0.13
• NI Simple Messaging (STM) Library >= 3.0.0.4

Source Code and Issue Tracker:

• https://github.com/NISystemsEngineering/CVTClientCommunication/
• https://github.com/NISystemsEngineering/CVTClientCommunication/issues

Download

• CVT Client Communication (CCC) Reference Library on LV Tools Network

Version 3 of CCC requires version 3 or later of CVT and STM.

Support and Feedback

Feedback and discussion on the CVT-based reference designs can be found here: https://decibel.ni.com/content/projects/cvt-based-reference-designs-for-machine-control