Trouble using a mask on a waveform chart

[TCC123]

I have created a waveform chart that plots the temperature readings from my thermocouple.  It is making continuous readings, and I can take the data from the text file I created and graph it in excel and everything is fine.  However, my temperature readings have to follow a standard temperature vs. time curve with a limit of 10% error.  Since I need to me able to compare the live data to the standard curve, I created a mask by inputing the data points for the upper and lower limits and hooked it up, and now my chart will not work.  When I checked the data on the text file it only makes 3 readings and then starts over (i.e. gives a reading at 0 sec, 1 sec, 2sec, then starts over).  I have tried using N readings instead of continuous and nothing seems to work.  Can anyone help?

Thanks!

[CarlaU]

Hi TCC123,

Can you maybe post a screenshot of the block diagram? Also, can you explain a bit more by what you mean of  "creating a mask by inputing the data points for the upper and lower limits and hooked it up, and now my chart will not work?" Can you tell us what you expected to see versus what you are seeing? Also, what hardware are you using? Thanks!

Carla

[TCC123]

Carla,

Attached is the program I made.  I am using Labview 8.2 with a NI cDAQ-9172 chassis, and a NI 9211 input module.  By inputing data points, I meant that I took the required data from the temperature vs. time curve I have to follow and placed them in the table that the masking.vi allows and set dx=1. 

Basically, what I am expecting to happen is that I will have a chart with streaming data of what the current temperature inside the oven is, along with the upper and lower limits of what the temperature can actually be.  This way, I will know whether I need to heat the oven up more or cool it off (the testing will last 4 hours).

I attached an excel file of the actual curve to give you a better idea of what I am talking about.

Thank you for the help.

[CarlaU]

Hi TCC123,

Thank you for the information. I have been looking at the VI and I think that the problem may  be with the Masking and Limit Testing VI. I found two great discussion forums that talk about setting up this VI. There is a great example in the Mask & Limit Express VI forum. This other forum also has some good information about setting up the limits. I hope that helps. I'll keep playing around with it on my end as well and I'll let you know what I come up with.

Carla