storing waveform data on the same graph

[coolmoodster]

Dear NI,

I am acquiring waveform data and want to display it on a graph. The problem occurs when I am trying to to keep the old waveform and store another one on top of it (superimposing). The waveform I sample is for 1 second and occurs periodically every 4 seconds. The waveform is very similar and I want to collect the data by keeping the graph full of every sampled data waveform. I am not sure if it is possible to do this.

Two recommendations were given: 1) use of a shift register and 2) the align waveform vi. I tried both with no success.

Please advise

[Shea C]

Hello coolmoodster,

Thank you for your question regarding superimposing data on a waveform graph.
You mentioned that you were collecting a one second sample every four seconds and then wanted to view this data along with previous samples on a waveform graph with the new data written on top. One possible solution as you mentioned might be to use shift registers to store the previous data set while acquiring another sample. You could add as many elements as needed to display as many previous data sets as you would like. I have attached a sample VI that might help you get started. The for loop iterates 50 times every 20 mS. This simulates your one second sample and the for loop has a 4 sec wait to simulate the sampling period.

Other resources can be found on
the ni.com website by clicking the support tab at the top of the home page. Under the third support option there is a link for example code. This will take you to a link where you can search for other sample code to help you get started. I hope these resources help! Let me know if you need any other support with this issue.

Shea C.
Applications Engineering