signal aquisition

[IDD]

I am making a VI code that acquires 2 of the same imputs from a signal generator. First, I need to be able to program it to display either one or both of the signals at the same time. Right now, I can get both to appear at the same time, but i need to be able to disable one from the font panel. How should I do this? Second, when both signals appear on the front panel, there seems to be a delay between them though, though they are identical signals. I need to get rid of this delay so that they appear as if one is on top of the other. Please help if you have any ideas as to how I should go about fixing these problems.

[Otis]

Hello IDD,

I saw that you are trying to do some manipulation of the data that you acquire by selecting which data to display on the graph that you are using. I also saw you had a question concerning the phase lag that you are seeing between the measurements of the same signal.

1. I did a quick search of ni.com by typing 'remove graph plot' in the search field. The following example should help point you in the right direction about how to plot multiple things on a graph:
   Programmatically Selecting Plots to Display on Graph
   
   Another way to look at a graph is simply that it plots whatever data it is given. You can always just choose to only pass a certain amount of data to a graph and then plot that data. One way you could do this is acquire the data as a 2D Array, then use the commands in the Array pallette (such as index array) to pull out the data that you want to display.

1. The phase lag that you are seeing between the signals is expected. You have a PCI-6220 which is one of our Multifunction I/O boards. One thing about this board is that there is only 1 analog-to-digital (AD) converter for this board. If you want to sample multiple channels then those other channels are multiplexed onto the AD converter. That means that there is a slight phase lag between one measurement and the next.
   
   If you need a board that can sample multiple signals truely simultaneously then please take a look at our line of Simultaneous Sampling (S-Series) Boards. You might want to look at the PCI-6143 as it has most of the same specifications that your PCI-6220 has.

I hope that these two solutions help you find the best answer for your needs.

Regards,