Problem with Extreme Negative Saturated Signals

[Tino_1111]

I am currently having major problems with the readings that I am getting with my thermocouple program. As shown in the attachment there are extreme negative spikes that go to -2000000. I don’t believe that this could be the program but I was concerned mainly because my minimum value to be read, as specified AI Temp TC, is 0 degrees celsius. Could someone tell me why it may be going to negative saturation and how to prevent this from being read in labview. I will be posting this question in the hardware forum to check if it may be the components that I am using.   New UserLabview 8 UserUsing SCB-100PCI-6071E

[Hueter]

Tino

I had some extra time today so I went through your code and made some changes that should fix your problems make a few improvements. 

1. The primary reason your data getting all of the bad values is that you had the DAQmx Create Task, Start Task and clear Task inside of your main loop. So evey cycle you were deleting your old task and creating a new one. Instead You should create and start the task before the loop, and clear the task and report errors after the loop finishes. You want to report the error outside the loop otherwise if there is an error you willbe stuck in a loop until your timer runs out. I also added an error status check in the loop, so if there is an error it will exit the loop then report the error.

2. You had a large structe using the split signals and several dynamic data conversions that was overkill. Based on the output to the front panel it looks like the purpose was to tellif the value was greater than zero for a given signal. I use 1 single greater than zero node then use an array of booleans. I had to make the indicators quite large so they would match the graph but the interface is very simple. It is not exactly equivilant but I think it achives the same goal with alot less code.

3. I made a few organizational changes to the front panel that make the UI a little easier to use.

4. Lastly, once you set all of the default settings (CJC,Therm type) like you want go to Edit>>Make current values default so everytime you open this program it will allready be initialized.

 

 

Let me know if you have any questions.

-Hunter

Message Edited by Huter on 05-13-2009 06:08 PM

[Tino_1111]

WOW!! I never had in mind that someone one help me this much, I truly appreciate it. I will need to try yours out to see if this will work,but I only have Labview 8 so the file you have attached will not work with my version. Is there a way to convert it if possible, if not I just go by the images on the message. I'll have to check if this will get rid of the negative saturated signals that I am getting. I'll let you know. Thank you so much Hunter!

[Tino_1111]

So I got it to work and it looks GREAT! The question I have know is how do I create buttons on the side of the waveform to turn on or off a specific analog input. It works if the AI is typed in but how should it be done if you have a buttonfor specific anaolg inputs? Also why does the minimum range for temperature not work. I have had this problem always from the beginning which is the dreaded negative spikes... Thanks Huter.

[Hueter]

Go to the example Finder (Help>>Find Examples) and do a search for select signals and open up the select signals example VI.

 

Message Edited by Huter on 05-15-2009 04:03 PM