Streaming Data

[nishit]

Hello,

I am working on a system to monitor a stream of data sent by an application to Labview (say via UDP). I am using Labview as a graphical query model to this streaming data to support "queries" like, plot pdf, cdf, sample etc. I want to create a library of VIs eg:

1. Generate Stream (which will do UDP receive)

2. And a bunch of other predefined VIs which allow different queries

I am running into the following issue:

The data rates of each VI can be different. Eg: in the figure

, the Generate stream output needs to be sampled and only the Nth data passed on to display.

In a way, each VI needs to have its own while loop. I can make the VIs communicate via sockets or local_global variables, but then I lose out on the advantage the user can have by specifying the query as a graph of VIs one provides in any order. (there will be no logical wires connecting the VIs)

Any suggestions?

Thank you,

Nishit

[JackHamilton]

Download File:post-37-1103031218.viNishit, [Pronunced 'Nis -hit' right?]

You need to use messaging to propogate the UDP data to other loops. Notifiers would be best as they support one message ->many receivers.

Looking at your example code - that won't work because the wire between the VI's will enforce standard LabVIEW execution rules which are:

The first VI will execute till completion - then pass data (via the wire) to the next routine etc. Wire connection in LabVIEW enforces exection order.

Your final code will contain many loops; one the UDP -> notifier send. Then the other loops will wait on the notifcation data or user options.

You can include a User Interface loop with a LabVIEW event structure and use the notifiers to pass commands to the various display loops (for configuration purposes)

Give that a try. BTY: UDP is not a 'reliable protocol' so it can lose data if network traffic gets high.

Attached is a quick VI showing this messaging and a snapshot of the diagram

Regards

Jack