Mixed Signal Waveform Graph

[Vills]

Hello Ravens,

The same program in LabVIEW 7.1 is showing some other error messages. Please help me with this. Please find the attched file. I need to take readings from two thermocouples (Thermocouples are connected to NI cDAQ-9172) and plot the two graphs on a single waveform graph.

Thank you,

Vilas

[RavensFan]

You are taking the dynamic datatype (which already contains both sets of data) and converting them to a cluster, then creating a 1-D array of that cluster.

Just wire the dynamic datatype directly to the waveform graph.

Note that since the graph is outside the loop, it will only display data once the loop is stopped.

Message Edited by Ravens Fan on 03-11-2009 04:05 PM

[Vills]

However, even after the program execution, the graph is not displayed at all.

[RavensFan]

You do have a graph, but it is probably just two single points because the DAQ assistant is set for N channels 1 sample.

Try putting a Waveform chart inside the loop.  It will take the data by points and store the previous points in its history.

You will still have issues with writing to a file because the same single point data is coming out.  You may want to build the single points into an array using shift registers and send the data out of the loop as arrays to log to the files.  (Or log to the files inside the loop, but that isn't as efficient because you open the file, log a point, close the file on every loop iteration once per second.)

[Vills]

Hello Ravens,

I tried to take the waveform graph inside the loop, however with no success. The waveform shows the correct temperature for both thermocouples during program execution, however graph is not displayed even after the program run is complete

Thank you,

Vilas V Jangale

Message Edited by Vills on 03-16-2009 11:41 AM

Message Edited by Vills on 03-16-2009 11:43 AM

[RavensFan]

Your images do not show up because you embedded images that are located on your hard drive.  I don't have access to your hard drive for them to be able to show up.  You must attach the image files to your message.  Post the message.  Then Edit the message inserting the image based on its URL located on the NI webservers.

Second.  You are still using a Waveform graph.  I said to place a Waveform Chart inside the loop.  They are two different entities. The chart maintains a history of what was sent to it and appends new data to it on every iteration.  A waveform graph just places the new data, the old data is wiped away.

[Vills]

I have connected two thermocouples in two different channels. However while taking an output from the DAQ system in the block diagram to two different waveform charts, how to differentiate between these two outputs?

Cause both the waveforms show the same graph (that is for, say thermocouple 1) and the temperature changes in the otherthermocouple are not shown on the corresponding waveform chart.

Thank you,

Vilas V Jangale

[RavensFan]

You've changed your DAQ assistant.  Now it is only reading 1 thermocouple.

Once you fix that, you will have to fix one more thing.  To put each thermocouple on its own thermometer display, you will have to use the Split Signals VI to separate the channels from the blue dynamic datatype and send each output to each T/C indicator.

Message Edited by Ravens Fan on 03-16-2009 04:40 PM

[atex]

I have an application very similar to the original post, but 24+ plots formatted into a DBL 1D array. Directly wiring to a waveform chart works great, but I like the organization of the mixed signal plot for this application. Any thoughts on how to do this---ideally with a for loop?