xy graph multi plots

[Atyab]

Hi John,

For my case I get the data whenever I receive an external trigger. Of course the trigger is being read inside a loop but the data isn't generated using a loop. It is read using a SCB-68. When I talked of not using the loop I was refering to the previous examples in which everyone used a "for loop" to generate the data for the plot.

[Dennis_Knutson]

Any of the examples that use a for loop, are just using them to create arrays and are a substitute for harware that is generating arrays. You have to replace the for loops with your hardware functions.

You are certainly not reading data from an SCB-68. A SCB-68 is just a dumb terminal block that is not capable of data acquisition. You must have an actual data acquisition board and while it help to know what kind, it's more important to know how you are reading the data. Is it multiple samples at a time, multiple channels at a time, etc. It would really help if you could simply attach your VI to see what is going on and exlain a bit further about what you want to do.

[Atyab]

Hi Dennis,

          Well, I'm actually using a NI PCI 6221 connected to a SCB-68. I'm taking only one sample which is logic one in normal state and logic zero when triggered. On its triggering I have to take the data and plot the graph. I have attached a sample program which shows exactly what I am doing. In place of the Random Number generator I am getting my numerical data from an image processed IEEE 1394 image. The image processing takes about 600 ms. Thats why I placed a delay in the Case Structure.

         Now, what I want to do is that before the trigger is detected, I want to plot a threshold line and after that take in data and plot it as a second plot on the same graph.

Looking forward to a solution. 🙂

[Atyab]

Hello! Anybody here? I would really appreciate if you guy reply.

Thanks

Atyab

[Atyab]

Hi, Since nobody is replying so I'll ask the question again.

Hi Dennis,

          Well, I'm actually using a NI PCI 6221 connected to a SCB-68. I'm taking only one sample which is logic one in normal state and logic zero when triggered. On its triggering I have to take the data and plot the graph. I have attached a sample program which shows exactly what I am doing. In place of the Random Number generator I am getting my numerical data from an image processed IEEE 1394 image. The image processing takes about 600 ms. Thats why I placed a delay in the Case Structure.

         Now, what I want to do is  to plot a threshold line before the trigger is detected and after that take in data and plot it as a second plot on the same graph.

Looking forward to a solution.  

[Dennis_Knutson]

What exactly is this 'threshold line' that you want to plot. I don't see anything in your code for a plot other than the random number generator.

One of your basic problems is that you have the graph terminal inside your case statement. You've made it very difficult to plot anything before the case is true. Just look at the examples for multiple plots and have the terminal outside the case statement so that you can write the threshold line continuously as well as whatever data you acquire when the case is true. In the false case, you can use a -inf value and that will not appear on the graph. I think you would also be better off not using the Express VI to create the graph.